About Adolf Goetzberger
Adolf Goetzberger is an applied physicist who has specialized primarily in semiconductors and solar energy. He studied physics at the University of Munich, working with Prof. Gerlach. He worked for Siemens from 1959 to 1962, at the Shockley Laboratory from 1962 to 1968, and at Bell Labs from 1968 to 1973. He was director of The Institute for Electrical Materials (The Institute for Applied Solid State Physics) from 1973 to 1980, and director of Institute for Solar Energy Systems from 1980 to 1994. He is currently retired.
The first part of the interview begins with Goetzberger's early years and education in Munich, and his experiences working with germanium transistors at Siemens in the late 1950s, but concentrates on his work as a scientist in California. Goetzberger describes his work on silicon semiconductors at Shockley’s laboratory, particularly in the research of P-N junctions and the development of the gettering stop, and his work on MOS at Bell Labs He emphasizes the importance to his career of Shockley, as employer, inspirer, theoretician, and collaborator, primarily at Shockley’s laboratory but also at Bell Labs. The second part of the interview focuses on Goetzberger’s career as a scientific administrator in Germany, and details his support of pioneering advances in liquid crystal display technology as director of the IEM/IASSP, and his work on photovoltaics and solar energy as director of the ISES. He mentions his association with and organizational work for the IEEE, as well as for the International Solar Energy Society. He discusses books and persons he has found to be particularly influential. The interview concludes with a discussion of various projects he is undertaking in his retirement.
About the Interview
ADOLF GOETZBERGER:An Interview Conducted by Frederik Nebeker for the Center for the History of Electrical Engineering, 5 September 1994
Interview #229 for the Center for the History of Electrical Engineering, The Institute of Electrical and Electronics Engineers, Inc., and Rutgers, The State University of New Jersey
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It is recommended that this oral history be cited as follows:
Adolf Goetzberger, an oral history conducted in 1994 by Frederick Nebeker, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.
INTERVIEW: Adolf Goetzberger
INTERVIEWER: Frederick Nebeker:
PLACE: Freiburg, Germany
DATE: 5 September 1994
Nebeker: When and where were you were born?
Goetzberger: I was born November, 1928 in Munich, Germany.
Nebeker: So you were a youngster when the Nazis came to power.
Goetzberger: Yes, I was quite young then, at the end of the war I was sixteen.
Nebeker:: What did the war mean for your education? Did it disrupt things?
Goetzberger: Yes it was heavily disrupted. Of course before the end of the war I went to school under the Nazi regime and we got all this ideological education. But it was countered in my home because although my father died when I was very young, my mother was opposed to the regime so I was usually up to date on what really to think of these things.
Nebeker:: Were you living in Munich?
Goetzberger: I was living in Munich. When the war really went into its last phases, we were directly effected by bombing raids on Munich. Our house was destroyed and we had to move away to stay with to some relatives.
Nebeker:: You weren't there in the house?
Goetzberger: Oh, yes. But there were air raid alarms almost every night, and everybody had to go to shelters in the basement. This is how we survived.
Nebeker:: How did it go with your education?
Goetzberger: Well I lost about one year after the end of the war, only formally, but I guess the education itself was also somewhat underrepresented. I got through Gymnasium, and started university in Munich. It was also in a very bad condition then because most of the buildings were destroyed. Equipment was missing and so on. I think I did not have a very good education as far as the material conditions are concerned. But I learned very early that this is not of much importance. For instance, in my doctoral thesis I had to get by with very simple equipment which was available. I did study physics.
Nebeker: You were in physics?
Goetzberger: Yes. I managed to discover some new effects with the things that I had and this gave me the chance to finish relatively quickly.
Nebeker: Were you always interested in science?
Goetzberger: Oh yes, by the age of fourteen I had already decided that I was going to study physics.
Nebeker: Did you play with radios or other circuits as a youngster?
Goetzberger: I did do this, but I'm not a very practical person, so these attempts did not get very far. [laughter]
Nebeker: So you thought of physics rather than engineering.
Goetzberger: I thought of physics because practical technology was not my strength.
Nebeker: Then you took the scientific line at Gymnasium?
Goetzberger: Well we did not have this division then. We just had one Gymnasium which had everything-- languages, mathematics and so on
Nebeker: And at the University of Munich you studied physics?
Goetzberger: I studied physics and was also involved in taking a lot of mathematics.
Nebeker: Can you tell me about your doctoral work?
Goetzberger: Yes, my thesis advisor was Professor Gerlach, who is well known in physics because of his experiments in quantum mechanics. I started my doctoral thesis in solid state physics which I continued later on. I did work on a rather obscure topic and that is the crystallization of evaporated amorphous films of antimony which had an interesting property which still attracts researchers today. When you evaporate it, it is first amorphous, but this is a meta-stable phase, and then it changes to the crystallization state from certain nucleation points. You could see how these points grow. I did some experiments looking at the kinetics of this transition.
Nebeker: Was this interesting because of the physics of it or was there some application?
Goetzberger: There was no application whatsoever. It was just the physics of it. The one thing that I added to the knowledge was that if you evaporate these films rather rapidly then you have a rather thick film and these are so unstable that they recrystallize in an explosive phase. So in an explosive version these things go very rapidly. I took some high speed photographs of that and this was actually the new thing that I was able to add. This now led to the result that my doctoral thesis was finished relatively quickly.
Nebeker: You said that you were constrained by the equipment that was available. So you had to choose a topic where you could do all the necessary work.
Goetzberger: Yes, that's right. In fact it turned out that because the vacuum in our evaporator was not so good that this effect was actually enhanced. I might not have found it in a very good vacuum.
Nebeker: How about the high speed photography; was that a difficulty?
Goetzberger: Well it was not very high speed, it was something you could do with normal equipment. You just had to run a normal camera at its highest possible speed. This permitted us to get this effect resolved.
Nebeker: So your work was demonstrating and also explaining this?
Goetzberger: Yes. Of course then I did the necessary mathematics to explain this transition and that basically finished my thesis then.
Nebeker: What did you then do?
Goetzberger: Then I stayed in Munich. Munich is a very attractive city. If you live there you don't go away so easily. So I found a job in Munich which was at Siemens. At that time I started with semiconductors.
Nebeker: What year was this?
Goetzberger: I think it was '59. Then I joined the semiconductor manufacturing department and started working on the development of transistors, which at that time were Germanium transistors.
Nebeker: Was there a research division of Siemens at Munich?
Goetzberger: There was also a small research division at Munich at that time, but they had the bigger laboratory at Erlangen at that time and they moved to Munich only later on.
Nebeker: And where were you?
Goetzberger: I was not in the research division, but I was at the factory, so to speak, developing devices.
Nebeker:: What specifically?
Goetzberger: I was working on alloy Germanium transistors which were at that time the standard product. Specifically, I developed a medium-powered Germanium transistor because at that time they had only a low-powered transistor, and they wanted to expand it to higher power to power little radios with it. That was about the state of the art at that time.
Nebeker:: And Siemens was producing transistors.
Goetzberger: They were producing transistors. They had a license from Bell Laboratories as usual, as everybody else at that time.
Nebeker:: And these were for radios?
Goetzberger: Well the smaller ones were mostly for hearing aids. That was a unique market for transistors because no other amplifier would fit into a hearing aid. And this is how transistors really started--in a small niche market.
Nebeker:: And then by that time radios were becoming familiar.
Goetzberger: By then they continued to radios.
Nebeker:: How long did you stay at that?
Goetzberger: Oh, I stayed about three years. It was actually quite long because I started to become dissatisfied with work I had to do at Siemens. The work mainly consisted of getting literature from the United States and then trying to repeat what they had done before. This was, in the long run, not very satisfactory to me. Some of my colleagues had already gone to America and I decided that this would be the right thing for me to do if I wanted to develop professionally.
Nebeker:: Before going to the next position, were there other things you worked on in those three years at Siemens?
Goetzberger: Well it was mainly the technology of these devices. I worked on the physics of transistors, also. It was not entirely understood at that time. I published a few papers on the reasons for current amplification, but it all revolved about transistors, particularly Germanium transistors.
Nebeker:: Then what did you do?
Goetzberger: Well, then I looked around what else to do. As you know eventually I ended up with Shockley in California. This had a rather interesting connection because Shockley belonged at that time to Beckman Instruments. And they had a subsidiary in Munich, a small factory and servicing center for spectrometers. One of my former colleagues from the physics institute worked at Beckman Instruments in Munich. He told me that Shockley was looking for additional staff. So I decided to put in an application, which at first did not work out very positively because I got a reply that they didn't need any additional staff at that point. So I thought the whole thing did not work out and didn't do much else. The situation at my job had improved again, but then suddenly and without any warning I got a phone call at my laboratory that Shockley was in Munich and wanted to see me. We made a date and I met him and Mrs. Shockley who had accompanied him. I later learned that she was very influential in who he hired because she was a psychologist.
Nebeker:: So she came to the interview?
Goetzberger: Yes. Also asked a few questions. Maybe some background which I did not know at that time. Shockley suddenly needed staff again. You probably know the history of Shockley laboratory in Palo Alto. Shockley had done all this great work at Bell Laboratories and after he received his Nobel Prize. He decided he wanted to go into business and got money from Beckman Instruments to set up his laboratory in Palo Alto. He had hired a very good staff, but just at that time before he came to Munich most of those people had left him. And this was actually the beginning of Silicon Valley, because all these people went out and founded a few transistor companies. They had had some disagreements with Shockley about which devices to develop. Obviously they were right because they were very successful.
Nebeker:: Was that to Fairchild?
Goetzberger: The biggest number went to Fairchild, but there were about twelve people and there were some smaller companies founded in silicon Valley. Of course it was not silicon Valley at this time because there was only this nucleus of Shockley people who had been assembled there in this area. Because they liked it there they just started their businesses there. So this was the background-- why he suddenly had vacancies again. I didn't know about this but I was happy anyway because I was being considered again. We had a very interesting talk and he asked me all sorts of questions. But what really made the difference was that from the literature I had decided I was going to propose a new type of transistor which had certain advantages. But I could only design it on paper because we did not have the technology at the time. So I had this design finished but nobody who had seen it was interested. I showed it to Shockley and he asked about some details and was satisfied that everything worked. This convinced him that I could do some original work. Very soon I received an offer and accepted it immediately and started out in California. That was about 1962.
Nebeker:: Can you tell me about that transistor that you had designed?
Goetzberger: It was a type of drift transistor and I'm afraid I don't remember the details. Anyway, it was never realized in practice. It would probably have worked but it was superseded when the development went to silicon transistors and the one I had designed was a Germanium transistor.
Nebeker: Was Shockley working on silicon at the time?
Goetzberger: Yes, he had already started working with silicon although he did most of his original work with Germanium. But he had very early on realized that silicon would be a better material, but it was at that time technologically very, very difficult to work with. But he had started a considerable effort on silicon devices.
Nebeker: So that was 1962 that you went to Palo Alto?
Nebeker: And what did you do there?
Goetzberger: Well I was hired as a senior scientist, which was a good title. I had a big surprise when I first saw the laboratory. It was an old barn, a big hall with lots of empty spaces. On the floor there were diffusion furnaces, and measurement equipment, and everything.
Nebeker: It didn't look like a German laboratory.
Goetzberger: It didn't look like a German laboratory at all! It had been improvised. There were a few offices built into this big hall. It was of course not very clean, which was the reason we had so many problem with our technology. Everybody knows this today, but at the time it was just not known.
Nebeker: Did you have an office yourself in that building?
Goetzberger: No, we had an office for four people. One of them was C.T. Sah, who was also with Shockley at that time. An another one was a Swiss gentleman, Kurt Hübner, and then our manger was there at that time. We were all crammed into one office. I spent a lot of time in the laboratory. I was given one technician. The type of work was not very well defined, but this was actually to my liking because I had some liberty as to what to do. I was given the job of discovering the workings of P-N junctions, to look at the qualities of P-N junctions and to look at reasons for breakdown phenomenon at high voltages.
Nebeker: Was this in silicon?
Goetzberger: It was in silicon. And in the technology I had a technician who did all the diffusions and contacting and so on. So it was actually a rather good set up because it was a wide open field.
Nebeker: Did you publish results in this field?
Goetzberger: Oh, yes. There were a lot of publications in this field. In fact some of them were so basic that they are still part of the present semiconductor technology. We found out at that time how to make good junctions and how to work with, well, under the conditions we had at that time.
Nebeker: So, did Shockley encourage you to publish?
Goetzberger: Yes, I can say I always had very good collaboration with him. Maybe one reason was that he was an excellent theory man. Anybody who did theoretical work in his laboratory had a hard time because he knew the theory better and usually he was right. So I had agreed that I would be in charge of the experiments and he would do the theory and this turned out a very good collaboration.
Nebeker: Did you work often with him?
Goetzberger: Yes, because he had only a staff of five scientists, so I worked with him practically every day.
Nebeker: Was he following the course of all these experiments?
Goetzberger: He was directly involved. He was very often in the laboratory sitting in front of an oscilloscope measuring characteristics of devices.
Nebeker: How was he to work with in that context?
Goetzberger: Well he was of course extremely smart. Almost every day he called everybody in the office and told us what new things he had invented since yesterday. It was exciting because it was very new. Not everything was practical but it was ingenious. He invented new devices much faster than we could realize them.
Nebeker: Did that cause friction?
Goetzberger: He was impatient, but on the other hand he was interested in the practical problems. He had coined an expression which he discussed in many meetings. This is what he called the "Respect for the scientific importance of practical problems." He said that every practical problem has a scientific background, and so whenever we had a problem in the laboratory we described it to him and he started to think about what would be the reasons for it . He would design new experiments to find out, so when we made slow progress with his new devices we could always interest him in the reasons why it didn't work. So he was occupied.
Nebeker: Did you work as a large team, or was it you working with Shockley on one set of experiments and the other scientists doing others?
Goetzberger: Of course, we were very short of manpower. We had many government contracts and so everybody was fully busy. So it was more like the second situation you described. Every scientist had one or two technicians and he had a large project for himself. Shockley interacted with everyone directly, but we were also informed what the others were doing because we had frequent staff meeting in which the work of everyone was discussed, so we were not isolated from each other.
Nebeker: But the experiments you were doing, you were doing by yourself.
Goetzberger: I was responsible for that myself. One of our important results was to understand why P-N junctions would at times have a very soft characteristic and break down. This was first was based on an idea by Shockley who came up with the idea that there are metal precipitates in the P-N junction. If you heat up the silicon the diffusion stage, then small traces of metals might get into the material. Solubility is higher at a higher temperature and so when you cool it down, those will form very tiny crystallites. If one of them happens to be in the P-N junction then of course it will short out the P-N junction. Shockley had developed this theory, but he had no proof for it and so he outlined several experiments that one could do in order to prove that point. We did a very beautiful experiment in which one of my technicians did a potential map with a flat diode. The potential map showed concentric rings with one point where the current was flowing through the junction. This indicated that we had at least localized current flow and that formed a part of an important publication we made. But having recognized this effect, one had to find ways around it because we could not operate under conditions that were so clean that we could avoid these metal contaminations. More or less by accident I found a technology which gave us perfect junctions every time. This is the gettering step which is customary today in semiconductors. It's actually a special variation of the normal diffusion. If you have a highly phosphorous, doped film of glass on the silicon then this glass will pull out these impurities. This then really gave us the possibility to make good junctions.
Nebeker: That was your discovery?
Goetzberger: Yes. I found it by observing under which conditions we got good or bad P-N junctions and then figuring out that it was this step that caused it. Then it was rather straight forward. Shockley of course was quite happy about this and the next thing we did was that we booked a plane to Bell Labs and showed it to the people there. They were also quite enthusiastic and invited me to a talk at the next IEEE meeting. So relatively quickly I had a rather good reputation among my colleagues, and this also showed to me I had done the right thing in going to America.
Nebeker: Was that process patented by you?
Goetzberger: No, it could not be patented. Shockley tried to have a patent attorney work something out but it turned out it was so general it could not be put into a patent.
Nebeker: How was it at that time for you to be working with Shockley?
Goetzberger: Well I found it actually very exciting because I had never worked so closely with a man of such great knowledge and I really had day to day contact with him. I could observe how his mind worked and how he arrived at new ideas. We had very good relations finally and he tested all his new ideas by first coming to me. I really felt quite privileged to work so closely with him.
Nebeker: Can I get you to describe your impression of his way of thinking through things?
Goetzberger: Yes. One thing that I think is quite characteristic for him, he had a very thorough theoretical understanding of everything he was working on. But then he always did some quantitative estimates of what he was looking at. This is quite important. He did not elaborate calculations, but his calculations were specific. You could say they were done on the back of an envelope. He put in very rough numbers and this usually tells you the most important answers because it tells you is this effect in the right ballpark, can we expect anything out of it. Very often people spend a lot of time on something which is orders of magnitude below what they expected and all this can be worked out quantitatively very easily. In another way, whenever we started on an experiment, he tried to predict what we would find. A very important lesson I learned from him is that when you do something, first you should know what you expect. Very often you find something different but then at least you know it is different. You may have found something very important, but if you had not done this mental exercise before then you might just not know what to think of your result and you might just throw it away. So these are all very important lessons I learned from him and the other thing that I already mentioned that every practical problem has a scientific aspect to it.
Nebeker: How much was Shockley working in that time in the way a physicist traditionally works? That is just trying to understand phenomenon and how much was he working as a development engineer trying to get some device to work.
Goetzberger: Well at that time he had a commercial company, and although he never made money with it he always felt the obligation to come up with something he could sell on the market. So he did think very practically, as much as he could, but it turns out that his mind was very science-oriented and he often got sidetracked into purely scientific reasoning. But his starting point would usually come from a practical question.
Nebeker: How about with you? Did you feel that as a constraint that you always had to return to practical matters?
Goetzberger: I never felt that as a constraint because I always had the opinion that I wanted to do something that is of use in the world and until today I prefer practical work to the purely scientific. So I was quite in agreement with him.
Nebeker: How long did you work with Shockley?
Goetzberger: It was almost five years.
Nebeker: Something like '62 to '67?
Goetzberger: 1968 about, yes. I came at the end of '62 and it lasted till the end of '68. We did many things. We developed a new high frequency power transistor. We did a lot of work on junction breakdown and the avalanche effect. There we did less scientific work, but science was again related to the reasons why junctions have a given breakdown voltage and why you couldn't make it higher.
Nebeker: Any other projects you recall from that period?
Goetzberger: We worked on epitaxy, it was the beginning of epitaxy at that period. What we had not known, which would have been a great help for us had we known about it was the planar technology which was developed at Fairchild. We had heard rumors that at Fairchild they had a junction that was perfect--it wasn't at all subject to contamination or from the influences from the ambient. We couldn't imagine how this was done because we always took off the oxide and went through careful processing to clean up the junctions. But it was never as good as an original planar junction.
Nebeker: How did this period come to an end for you?
Goetzberger: Well it, the major reason was the lack of financial success of the company. However in the laboratory we survived quite well off government contracts. Because Shockley was well known he could always get another contract. But the manufacturing was always working in the red. He had invented a switching diode, a four-layer diode which he sold at that time, but the yields were not good in production and so it was usually losing money. The company changed hands a few times, then at one point we were sold out to Clevite. They tried to bring in new management.
Nebeker: How did that affect you?
Goetzberger: Well, at first it affected me very positively. They sidelined Shockley. He was no longer company president and he was more or less put into an advisory status and I became R&D manager. Shockley started to direct his attention to Stanford University where he later became a professor, but he still was very active in the company. We still continued our collaboration so it was not that my promotion had any adverse effect. We continued doing interesting work in the laboratory, but this didn't help our manufacturing at all because we worked on government contracts on very different problems. But even this arrangement did not work out very well, and Clevite finally brought in another general manager who was very narrow minded. He tried to get the scientists to keep certain working times, so every morning he was at the door with his watch taking notes on who was late. This of course annoyed our most creative people and they started to leave. At that point I decided it was also time for me to leave. This was not the only thing, he was just a very picayune man who thought that if you watch how many sheets of paper are consumed and how many stamps, then you could turn around such a company.
Nebeker: How large was the development group when you were heading it?
Goetzberger: It was about twenty people altogether. About six or seven scientists and they rest were supporting personnel. It was a very exciting time and I enjoyed it continuously with the exception of the end of course. Then I decided to leave Shockley because it was really easy to find another job because what I had to do was drop some hints to some colleagues and I've already got some offers.
Nebeker: What did you next?
Goetzberger: Then I decided to go to Bell Laboratories.
Nebeker: Before going onto that, how did you like living in the Palo Alto area?
Goetzberger: I liked it very much, particularly when it was not so crowded as it is today. It was a marvelous climate. San Francisco was very close, with all the cultural possibilities. So I found it very nice; only my wife was missing the seasons.
Nebeker: Did you know Shockley socially?
Goetzberger: Yes, I was quite often at his house and he was invited with us and so we had a lot of social contact. But of course his was a little withdrawn, you could never call him a friend really because there was still a large distance between us.
Nebeker: So you went to Bell Labs in '58?
Goetzberger: I went in '58, yes.
Nebeker: What was the position there?
Goetzberger: I first started just as a scientist. I started with another interesting project. I was there at the beginning of a technical important development it was the development of MOS devices and I started working on the physics of MOS. At that time MOS systems were unstable and uncontrollable but nobody knew why. With my previous experience with such phenomenon I was able to also come to some results rather fast there.
I have these books which were given to me by the people of the institute on my sixtieth birthday and it contains all my papers, with a few exceptions that were found later. So this is on metal precipitates.
Nebeker: That's 1960 in the Journal of Applied Physics.
Goetzberger: This is that potential plot I mentioned, and that's the model how the precipitate forms and is then also removed by gettering.
Nebeker: This must be one of the most cited papers in the field.
Goetzberger: It was cited quite a number of years, but now it is so old that it is general knowledge. There are many such papers from the Shockley center. These are the papers on avalanche effects. So I then wrote some review articles on avalanche breakdown. And at that point the MOS work starts, that was at Bell Laboratories.
Nebeker: Now was that something they hired you specifically to work on?
Goetzberger: No, at that point they didn't hire one specifically. I was hired on the basis that they expected to hire good scientists and then I was led around the laboratory and then I could decide which project I would like to join.
Nebeker: And that was the first one you worked on?
Goetzberger: That was the one I selected.
Nebeker: And how large was the group working on that?
Goetzberger: I was only working with one person. It was Ed Nickolian at that time. And we did some very interesting work which was more scientific. We just decided to explore the properties of MOS capacitors and we could do a lot of physics with it. Our standard paper is this, how to understand surface states in interfaces and how to measure them. This is one which is being quoted many times. Its a very long paper also. Its about 100 pages.
Nebeker: And that came out in '67.
Nebeker: And that was important I take it in the development of MOS?
Goetzberger: Yes it was quite important in understanding MOS devices and measuring the relevant quantities. So there are a large number of paper on the MOS system.
Nebeker: You said that you were later on put in charge of a group on MOS?
Goetzberger: Yes, it was a group doing MOS and there were such people as S.M. Sze in it. You may know him he has written several important books. Ed Nickolian, with whom I started; Neil Berglund who went to Intel, I think, later on.
Nebeker: And how large was this group?
Goetzberger: It was about five scientists plus assorted technicians again.
Nebeker: Were the, was the laboratory equipment better at Bell Labs?
Goetzberger: Oh, yes it was just excellent. At last we had everything we needed, or we could get it. Availability of materials or equipment was never a problem there.
Nebeker: And I take it this was important in MOS development?
Goetzberger: Well it was certainly very helpful not to be handicapped by such shortages.
Nebeker: Did you feel that way at Shockley? That you were held back somewhat?
Goetzberger: Since I had started in very modest conditions, I usually found a way around these problems. We always decided if this direction is closed for me then I take another one. I was never held back by the lack of good equipment if some other way was available. In fact today often researchers are handicapped by having some very complicated and expensive apparatus which they spend all their time just maintaining. This keeps them from making real progress.
Nebeker: How long did you work at Bell Labs on this MOS development?
Goetzberger: It was almost also five years.
Nebeker: And these were very fruitful years?
Goetzberger: These were very fruitful years, yes.
Nebeker: You liked the conditions there?
Goetzberger: Oh, yes. Bell Labs is ideal, or it was at that time ideal for scientific and technical work.
Nebeker: Which laboratory were you working in?
Goetzberger: That was the semiconductor device laboratory in Murray Hill. I had a house within walking distance from the laboratory and had very good circumstances there. I probably would have stayed there had I not received a very interesting offer from Germany.
Nebeker: What are the highlights, other than what you just mentioned, of that five year period at Bell Labs?
Goetzberger: Well, it was a very interesting time and a very interesting group of people that got together at that time, all working on MOS. We were all working at Bell Laboratories but there were other groups, one that was at RCA and also one at Fairchild, but we all got together at meetings. We organized a new type of meeting, the interface specialist meeting which got together to discuss the new results. That was in IEEE by the way. These were the three most important groups and some of the people became quite well known later on. One of them was Andy Grove, for instance. I still remember the heated discussions we had on how to make oxides best.
Nebeker: So it was a pretty open research area?
Goetzberger: It was a relatively open research area because at that time there was already some commercial interest in MOS transistors. The basic phenomenon was still rather freely discussed. At that time we had, for instance, some instabilities in the oxide caused by alkali ions and that was first published by Fairchild and that clarified an important part of the technology. But then they had a different way of doing it, of producing their oxides, and we always got different results. We were arguing about all these steps and it turned out that they had done one thing differently, and they hadn't even realized that it was a difference, so we never even discussed that.
Nebeker: Were there parts of the work which were not made public?
Goetzberger: At Bell Labs at least we were able to publish everything, although sometimes we were asked to apply for patents first. Never were things kept secret at Bell Laboratories at that time.
Nebeker: Were there any particularly inspiring or stimulating people you worked with at Bell Labs?
Goetzberger: Oh, yes. It was quite a number because Bell Labs was full of practically the best researchers that were at that time working. I had contacts with a very eminent theorist from the research department. V. Heine was a well known theorist, and interestingly I continued to have contacts with Shockley at times because his lab had fallen apart. He had accepted a job as a consultant for Bell Labs. He was there some days every month at Murray Hill. He gave me some ideas of what he was doing. One thing about Shockley was that he was never interested in more than one thing at a time. It was the only thing he could talk about. So if it wasn't his current interest there was no way of discussing it.
Nebeker: What was this interesting offer from Germany?
Goetzberger: Well it was to Freiburg, where I am still today. It was to become a director of Institute, well I changed its name, it was then Electrical Materials, but I changed it to Institute for Applied Solid State Physics.
Nebeker: This was a new institute?
Goetzberger: No, it was an existing one that already had more than a hundred people working in it. I was offered to take this over and put it in a new direction.
Nebeker: I'm sorry, what was the old direction?
Goetzberger: Well the previous director had retired.
Nebeker: What sort of work had the institute been doing?
Goetzberger: Oh, it was quite a conglomerate. They had one part that did silicon technology, but another part did infrared spectroscopy of organic materials. Still another part did microwave measurements. Still another did basic research on compound semiconductors.
Nebeker: When you came you decided you wanted to direct it more completely?
Goetzberger: Well of course this institute did not exist by itself. There were people and places that were funding it and were interested in certain directions. So at that time it was funded mainly by the Defense Ministry, and they were interested in new materials for microwave applications but also in silicon technology. Since this was my line of work anyway, I was quite willing to emphasize this direction. I also started a new department which was devoted to displays. I noticed that there was a very small group that worked on liquid crystals there. At that time liquid crystals were a very esoteric material with no known application whatsoever, but before I came back to Germany I had been at an IEEE meeting where I heard a talk by (George) Heilmeier who had invented the dynamic scattering effect in liquid crystals. It was at that point not very practical because it only worked at elevated temperatures, but it was already obvious that one could make a display out of it. So I revived this group, which had just been closed, and started them on work on displays with liquid crystals. This is still going on. At this institute they still have a strong standing in display technology.
Nebeker: So they were one of the early groups to be working on such displays.
Goetzberger: Yes, well they are more or less a center for that in Europe. And I started to introduce some work I was interested, so I continued work in MOS but I had less time from then on to do research because I was of course very much occupied with management jobs.
Nebeker: But you had managed R&D before, but I guess not on this scale.
Goetzberger: At the smaller level at which I had managed it it was really more or less active involvement. When I took over this Institute I had a small group of people out of one or two doctoral students that worked directly for me. I talked with them occasionally and gave them directions but beyond that I did not have time to do scientific work directly, but I kept some of it up all the time.
Nebeker: How was that; both returning to Germany and going to an academic setting?
Goetzberger: Well it was really not an academic setting because it was no university it was also a Fraunhofer Institute, which is an independent, but of course government financed institution. So a little bit later I also became a professor at the university more or less as a title and also it gave me the chance to have thesis students. I never gave more than two hours of lecture each week. I did not feel to be in an academic position but rather a research management job.
Nebeker: How was it returning to Germany after these many years in the U.S.?
Goetzberger: Well for me it wasn't overly difficult because the scientific problems were just the same. I had to get used to administrative procedures which were different in Germany and also because of our involvement with the government one had to get used to regulations and rules there. I had some very able advisors at the institute who knew everything, so I was able to delegate some of the more unpleasant things. It wasn't too difficult. My wife found it much more difficult to get used to Germany.
Nebeker: Is she German?
Goetzberger: Yes, but ten years in the States had an effect, and left a thorough impression.
Nebeker: May I ask in what way it was difficult for her?
Goetzberger: Well, she found everything much more complicated here. She always thought life in the U.S. is much easier. Which is true I think.
Nebeker: Did you have regrets later about leaving a research position at Bell Labs for heading an institution here?
Goetzberger: No, not seriously. Of course sometimes I would have enjoyed having more time for doing research. On the other hand I don't like stagnation so you have to make the decision at one point in your career to go beyond being a scientist and take on bigger responsibilities. This is just the way it goes. I also met former colleagues who stayed in research and they were not overly happy because they had much younger people who were their superiors and so continuing in research in this manner might not have been satisfactory. I could of course also have gone to university and started that career in this line but you do spend a lot of time on unproductive matters also at the university. So I don't really regret anything.
Nebeker: Can you sketch out for me how your years as director of the institute went?
Goetzberger: Well I did turn around the institute. I did try to improve the quality of the staff by getting rid of the less qualified people. I put in an entirely new management of the departments. One of the department heads, who was an Austrian, also came from Bell Laboratories. Another one came also from the United States. So the whole thing became a lot more effective. It was actually considered a very good research institute and this is what I think was the final result of the work. It was more directed toward, lets say, the needs of the operating agencies. We finally also managed to get it partly financed by the Ministry for Science and Technology. So it was open for civilian applications. We established good collaboration with industry. One thing I also enjoyed during that time was that I was an advisor to the government for the government contracts. So I could have, I hope, a positive influence on the type of R&D they had contracted.
Nebeker: You said that the institute changed its name?
Goetzberger: Yes. When I took it over it was called The Institute for Electrical Materials and then I changed it to The Institute for Applied Solid State Physics. So we get to emphasize mainly the semiconductor and the scientific aspect of it.
Nebeker: You mentioned some of the groups, but what were the main areas of work in those years?
Goetzberger: There was a silicon technology group which continued on the MOS work. Then we had an infrared materials group that was again created because of the interests of the defense people.
Nebeker: This is for imaging?
Goetzberger: For infrared imaging, yes. They worked in such materials as mercury cadmium telluride, and some tin compounds. Then there was a microwave group that was changed to high frequency devices. They worked in gallium arsenide and they also did some work on acoustic devices.
Nebeker: What sort of acoustic devices?
Goetzberger: These were delay lines and such things.
Nebeker: Is that closely related to microwave?
Goetzberger: Yes, they were used for phased-array radars and such things. I don't know what became out of it because it's been a long time since I left the Institute.
Nebeker: When was that?
Goetzberger: That was about 1980.
Nebeker: And what did you do then?
Goetzberger: Then I started this institute here. I was also made a Fellow of the IEEE. And I received the J. J. Ebers award of the Electron Devices group.
Nebeker: So you founded a new institute here?
Goetzberger: Yes, after twelve years in the other job I decided I was getting stale in it. I had realized everything I had intended to do and there wasn't much more I could do. I realized I needed something new. I found solar energy.
Nebeker: Is this something that some of your results led you to?
Goetzberger: In this display group we worked on a florescent enhancement of the display and it occurred to me that one could use that for the collection of solar energy. I have a sample of that here. This is the effect.
Nebeker: Very striking.
Goetzberger: It’s very striking, yes.
Nebeker: What is this?
Goetzberger: It’s a PMMA doped with a florescent dye. The light is absorbed in the plate. It is trapped by total internal reflection and it can only escape at the edges.
Nebeker: It’s quite amazing to look at that.
Goetzberger: Yes, we worked quite a while on this. I worked on the theory. This would be used for solar energy conversion. This is probably in one of these books also.
Nebeker: Is this the same material?
Goetzberger: It’s the same material, yes. It found most of its uses in advertising.
Nebeker: Let me just get the reference. This is florescent planar collector concentrators for solar energy conversion. Was something that was done at the institute?
Goetzberger: It was done at the institute and I had started to think about the use for solar energy and that made me aware of the energy problems. And at that time nobody was very interested in solar energy, but this is always the best time to start on something new.
Nebeker: So you had this idea that solar energy is a good area to develop?
Goetzberger: Yes, and so I assembled a small group at the old institute to work on solar energy. This started to develop and finally we separated it from the institute. We set up a separate working group which then after a while became an institute for Solar Energy Systems. Well I was directing both institutes, but this was of course not a very permanent arrangement. So I decided in 1981 to separate myself from the old institute, which still exists in Freiburg. It is even much larger than it was at that time. But my activity there is now mostly forgotten.
Nebeker: And it appears that this is a fairly large institute.
Goetzberger: Yes, this is something like more than a hundred people and it is the largest institute in solar energy in Europe.
Nebeker: And that was in '81 when you said it was formally established.
Goetzberger: It was formally established. It was about thirty five people or so.
Nebeker: Did you have to do a lot of work to find funding for it?
Goetzberger: Yes, it was very difficult because its always difficult to interest people to spend money on solar energy. We had a short period where we had a lot of funding and we made good use of it. For instance we installed a clean-room and this helped us to make very good solar cells here.
Nebeker: What have been the principle sources of money for the institute?
Goetzberger: That is almost exclusively the Ministry BMFT, the Ministry for Science and Technology. We got some money from the European Community. We get some from our state, but the bulk of the money comes from Bonn.
Nebeker: Is there not a large enough industrial activity in this area to have a lot of support?
Goetzberger: Well we have some industrial funding as well, but it is not more than ten percent.
Nebeker: What have been the highlights of this thirteen or fourteen year period that you directed the institute?
Goetzberger: We had many highlights, like we made the world's best flat plate collectors. We made the, for the solar cells, we most certainly make the best solar cells in Europe. Only Green in Australia makes better ones. And we have a calibration group established here which is in exchange with six or seven others around the world and they set the standards for solar cell measurements. The newest thing we have is the self-sufficient solar house. We built a house here in Freiburg which does not need any outside output of energy. It is only operated by solar energy. There's PV of course and the thermal technologies. Passive solar energy, it also has seasonal storage with hydrogen. That has seen a lot of interest--it was the first time that something like this was realized in our type of climate.
Nebeker: And it proved possible to do that?
Goetzberger: Well it is still not entirely completed. It works but then occasionally something breaks down and we have to still improve all the components. In principle it works.
Nebeker: And of course its also an opportunity to try out all these technologies.
Goetzberger: Yes, its a possibility to try out all the energy saving technologies, which are quite important. Well one important result was the development of transparent insulation materials that are of great help for all types of solar conversion. These can be used for collectors but also mainly for cladding of facades. We have now quite a number of demonstration projects of building in various places. All over Europe, so all these things have started here.
Nebeker: Maybe we could digress a bit here and you tell me what seem to you to be the real milestones in solar energy. In winning of solar energy over the last several decades.
Goetzberger: Well we have seen a lot of progress in thermal conversion and the technology of solar cells. Prices have come down quite considerably whereas ten years ago solar cells could only be used in satellites now they are quite common in terrestrial applications although they are still quite a way from being competitive with grid electricity.
Nebeker: In this development, are there two or three breakthroughs that can account for this, or is it steady progress?
Goetzberger: No, in fact it’s quite interesting that the basic material for solar cell is still silicon. Although numerous other materials have been tried, also introduced with great fanfare. silicon is still surviving. Of course this makes me happy because I had from the beginning already decided that we would work with silicon only. This means that we are still doing the right work. There may be some new materials some time in the future, but I expect it will be more and more difficult as silicon develops further. Just as in semiconductor technology, we are always thinking that silicon will be replaced by something else, but it never happens.
Nebeker: Have there been breakthroughs in the design of solar cells?
Goetzberger: Oh, yes there have been considerable breakthroughs. Improving the efficiency, for instance, we now have in the laboratory about three times the efficiency we had ten years ago. And something very surprising with solar cells, the efficiency is now higher than it was considered theoretically possible ten years ago.
Nebeker: How do you account for that?
Goetzberger: Well the theory has to be based on some structure, on some given design which then theorists think everything is optimal. Then they arrive at a maximum efficiency, but they did not take into account that people would find deviations from this basic design which would open up the possibilities. So the device design turned out to be quite crucial there.
Nebeker: What names are associated with these breakthroughs in design?
Goetzberger: Well the first one comes to mind is Green in Australia. And then the IEEE specialists meeting always contains the most recent advances. They also have a William Cherry award which they give to one individual who is considered the most productive one.
Nebeker: How important has IEEE been for you in your career?
Goetzberger: I have had a lot of contact with IEEE in my years in the U.S. I have been involved in organizing meetings. I was in the committee of the device meeting and there was a meeting of device research in which I also participated. I was once in the administrative committee of one of the societies.
Nebeker: The Electron Devices Society.
Goetzberger: Yes. So I did spend some time there. I was made a Fellow, which is also nice to have.
Nebeker: What about when you came to Germany? Have you been active in IEEE in Germany?
Goetzberger: Yes, I was active for a few years, but then I rotated out again of these positions. But then in recent years my emphasis shifted away from IEEE, I must say because IEEE only deals with one aspect of solar energy. All the others, particularly thermal conversion and architecture and energy storage are in other societies so I became a member of the International Solar Energy Society. I was active in this society, for the last two years I was president of the International Solar Energy Society.
Nebeker: Can you tell me a little bit about that society?
Goetzberger: Well yes. It is a world-wide society. It is not centered in any nation, but it is a world wide society with sections in about thirty or forty countries and members in practically all countries of the world. But still it's a relatively small society with about three thousand members altogether.
Nebeker: Does it have a journal?
Goetzberger: Yes it has two types of journals. This is one of them. This is the more popular journal.
Nebeker: The magazine type. This is Sun World.
Goetzberger: Then we also have a scientific journal, which is this one here.
Nebeker: Well I see it must be very old. This is volume fifty-three.
Goetzberger: This society, abbreviated ISES, is about thirty five years old now. It was founded in the United States, but then during some reduction of support in the United States, they couldn't maintain it there anymore and then it was moved to Australia. The headquarters are still in Australia, but it has now been decided to move the headquarters to Europe.
Nebeker: Did your presidency have anything to do with that?
Goetzberger: Well I initiated part of that. But then it was more or less a unanimous vote of the board of directors. They were no longer satisfied with the headquarters being relatively far away and the staff was relatively sleepy and so there was a lot of unhappiness. But our president is an American.
Nebeker: Does this Fraunhofer Institute have any formal connection with this society?
Goetzberger: Well we have quite a number of members of the society at the institute. I was president until recently and I am still a member of the board and my successor is also a member of the board.
Nebeker: Just a couple of other question I wanted to ask you. One of them is what books written by other people have been very influential to you in the course of your career?
Goetzberger: I could mention Shockley's book, Electrons and Holes in Semiconductors.
Nebeker: Did you make use of that before you got to know him?
Goetzberger: Well, I had only seen it, the possibility of using it in the library, but not too much in detail so it depended mainly on having one for myself and then I used it a lot more. Then I also find Semiconductor Device Physics by my friend Simon Sze very useful. All I have to do now is look at my bookshelf. Another one is Beckman and Duffy, Solar Energy Thermal Engineering.
Nebeker: I was just going to ask if there are any fundamental books in solar energy. I take it that is one of them.
Goetzberger: That is very fundamental. It just appeared as a new edition.
Nebeker: Were there any student texts that you had that you were perhaps very impressed with?
Goetzberger: When I was a student?
Nebeker: Any that you find stuck with you?
Goetzberger: No, when I was a student it was very difficult to get books and we had scripts of our lectures.
Nebeker: Oh, you worked with that mainly.
Goetzberger: Yes. But I have written two books myself, but they are in German. One on Photovoltaics and one on solar thermal conversion. These are books from my lectures.
Nebeker: I see. And have these found acceptance?
Goetzberger: Well, yes. These are being reprinted all the time. The photovoltaics book is now in its first edition but the other is in third edition. The PV book will probably now be translated into English.
Nebeker: I wanted to ask you about people you have come in contact with. And I neglected to ask you earlier about Gerlach, your thesis advisor, about him as a person.
Goetzberger: Well yes, he was a very universal scientist. He was interested in quite many ways of doing physics; magnetism, spectroscopy, optics. He was one of the old scientists who still was grasping the entire range of physics. So he was very knowledgeable. But also he was quite excitable. He could get very angry occasionally. I still remember that one of my student colleagues had obviously done something wrong and he got so excited that he threw him out of the laboratory. But the next day he regretted it and he got him back again.
Nebeker: Were you then careful in dealing with him?
Goetzberger: Oh, yes. I was very careful. But I did not have too much contact, because soon after I had started my thesis work with him he became head of the university. So he was quite busy with many official duties. It turned out that he was also a very educated man and could give talks on any subject, literature, philosophy, and so on. He was a very universally educated man.
Nebeker: Did he have any influence on your development as a scientist?
Goetzberger: By far not as much as Shockley did, because I just did not have enough contact with him. He taught me how to work independently by not having any contact with me.
Nebeker: I suppose that's a valuable lesson.
Goetzberger: On the other hand when I had my first results and I showed it to him, he was very enthusiastic and supportive.
Nebeker: You've talked some about Shockley. Are there other people you've come in contact with who have either influenced you personally or just have impressed you very much. Maybe they haven't influenced your work directly.
Goetzberger: Well, besides Shockley, I still remember a number of interesting, qualified people I met at Bell Laboratories. So I had some supervisors there like Bill Boyle and George Smith who invented the charge-coupled devices. I worked together with them for a while and this was a very rewarding experience. I already mentioned Andy Grove.
Nebeker: How did he impress you at the time.
Goetzberger: Well we were scientists just both of us and we had got along very well with each other.
Nebeker: Did he seem especially bright?
Goetzberger: Yes, there were many at that time that seemed especially bright. And so of course I didn't expect him to get that far along. I also remember Gordon Moore, having met him at that time. But I did not have any direct association with him, but with Andy Grove I had quite many contacts.
Nebeker: Any other people that come to mind immediately?
Goetzberger: Well my best friends is one who was at Shockley and also at Bell Labs, this was Hans Queisser whom you might know. He is director at the Max Plank institute in Stuttgart. He is quite well known in solid state physics.
Nebeker: Did you ever work directly with him?
Goetzberger: Oh, yes. We had the same office at the Shockley laboratory and did a lot of work together and also at Bell Laboratories.
Nebeker: I see. Was he in the MOS group?
Goetzberger: No. He was in a neighboring group and he worked on semiconductor lasers at that time.
Nebeker: What are your plans, what are your current activities since you have retired?
Goetzberger: Well at my age you do not have many plans. Just happy that I can continue with some of my work and contribute a few things. But I don't have big plans. So I'm doing, well I'm doing several things, I'm doing project work at the institute. I'm still heading up the project of the self-sufficient solar house. I'm helping my successor by helping out with representation and visitors occasionally. Then I'm giving lectures in many places. I'm doing a few consulting things like for the Hahn Meitner Institute in Berlin. Then there is a research association of all the solar energy institutes in Germany, for them I am doing R&D coordination. I haven't really started seriously with it because it seems to involve a lot of work. And then I'm also a partner in a small company that applies photovoltaics.
Nebeker: Is this something you founded?
Goetzberger: I founded it together with a Swiss colleague. This Swiss man, his name is Nordmann, has a company in Switzerland. Since Switzerland is not a member of the European Common Market, he needed an outlet within the common market so he approached me to found a German company together with him. And this we started only about half a year ago in Freiburg. It's not production, but it's engineering. He is a specialist in installing photovoltaics along motorways. You may have seen pictures of those motorways in Switzerland.
Nebeker: The design of such systems.
Goetzberger: The design and also installing them. He does the engineering for them and we now have a proposal in Germany. We also have some support from bigger utilities to do the same in Germany if it comes through.
Nebeker: Well it doesn't sound like you'll be idle.
Goetzberger: Yes, I notice that my retirement is not what its supposed to be. Anyway I also plan to attend the next photovoltaics specialist meeting which will be in Hawaii this year in December.
Nebeker: Good place for solar energy.
Goetzberger: Good place for solar. We already have from our company a paper that will be presented there.
Nebeker: Is there anything that I didn't ask about that you'd care to comment on?
Goetzberger: Maybe, well I should have mentioned that I am now a chairman of the German Solar Energy Society.
Nebeker: And you are still continuing on that?
Goetzberger: Well I started only last year. This will last for two years altogether and I can even be re-elected for one term. So I hope I stay active as long as this lasts.
Nebeker: Anything else you'd care to comment on?
Goetzberger: Not at the moment. I will certainly think of other things after you have left.
Nebeker: Well thank you very much.
Goetzberger: Your questions were quite pertinent.