Interview: Jane P. Chang
2005 Peter Mark Award Recipient
HOLLOWAY: Good afternoon. I'm Paul Holloway, a member of the AVS History Committee. As part of the Society's Historical Archives Series today I will be talking with Dr. Jane Chang, who is this year's Peter Mark Award winner. It is November 1, 2005, and we are at the 52nd AVS Symposium in Boston, Massachusetts. So Jane, I'm pleased to have you here today, and very pleased to talk with you. Congratulations on your Peter Mark Award.
CHANG: Thank you very much. I appreciate the recognition from AVS.
HOLLOWAY: It is a fantastic society, isn't it?
CHANG: It is.
HOLLOWAY: Just to begin, perhaps you could give me a little bit of information about your background and your past education and experience?
CHANG: Sure. I received my education up to undergraduate in Taiwan. So, I graduated from National Taiwan University in chemical engineering in 1993. I then went to MIT for my graduate study. And, I didn't know that I would be entering in the area of electronic materials until I heard a presentation by my research advisor Herb Sawin.
HOLLOWAY: Oh, is that right? So, could you spell Sawin for us?
CHANG: S-A-W-I-N.
HOLLOWAY: All right. This is a request for my daughter because she's transcribing some of these recordings.
CHANG: Sure. Absolutely.
HOLLOWAY: So, sorry. Go ahead. I interrupted you.
CHANG: And then I just found the area interesting and different from what I had learned as an undergrad, because in our curriculum we didn't have materials or courses covering this particular area. And, I wasn't sure if I would be able to take on the challenge in the new area, but Herb was very encouraging (Holloway: Uhm-hmm.) and basically told me that most of the chemical engineering students with an undergraduate background don't have much experience in the area. "As long as you're willing to learn, you will do well."
HOLLOWAY: So, what did you think you might be interested in when you first arrived at MIT?
CHANG: When I first went to MIT I thought I would be working for Bob Brown in fluid mechanic simulation, because my undergraduate thesis was on the Newtonian fluid flow simulation, and my undergraduate research advisor graduated from Washington, Seattle, working for Bruce Finlayson.
HOLLOWAY: How do you spell Finlayson?
CHANG: Finlayson, F-I-N-L-A-Y-S-O-N.
HOLLOWAY: Okay.
CHANG: And, he graduated from Minnesota working for Scriven, S-C-R-I-V-E-N. (Holloway: Uhm-hmm.) And so, I knew Bob Brown's work very well and he's certainly the top-notch researcher in the field. So, I thought I would go there and if I get a chance I'll work for him. (Holloway: Yes.) But then I had completely changed what I wanted to do from a very theoretically based field into an area that is almost purely experimental.
HOLLOWAY: Well, that's an interesting history. It's illustrative, I guess, of virtually everybody's career. They think they're going to go in one direction and they wind up going in another direction. (Chang: Uhm-hmm.) So, where did you go after you finished with MIT?
CHANG: Okay, so when I was at MIT I think one thing that really helped me a lot was the MIT Practice School. It was an internship that was established with industrial sponsors. So, the student can pursue a master degree in chemical engineering practice by doing an internship for one semester (Holloway: Uhm-hmm.) with two member companies. (Holloway: Uhm-hmm.) So, I went to that particular program, which is totally not related to my PhD thesis, but that particular program is pretty intensive and it prepares you very well for writing and presentation, because we had weekly presentation. And, at the end of each month we had to write up a summary report for our research. (Holloway: Uhm-hmm.) So, I personally thought that was a very valuable experience. And, finishing my PhD work I first started looking for industrial positions. And, that year the semiconductor industry was doing very well, so I had a lot of opportunities. But, after an interview I realized that maybe my interest would still be in the more fundamental science. Then I started looking for a postdoctoral position, and then I eventually decided to go to Bell Labs, Lucent Technology, (Holloway: Uhm-hmm.) to do my postdoc.
HOLLOWAY: And who did you work with there at Bell Labs?
CHANG: So, I worked with Bob Opila. He's now a professor at the Materials Science Department in Delaware. (Holloway: Uhm-hmm.) And, I worked an area that was very different from my graduate study and that particular experience really helped me in terms of defining what I wanted to do in the future, which is what I'm doing right now. (Holloway: Uhm-hmm.) And, the freedom he has given me in doing my postdoctoral work, and my ability to collaborate with many people at Lucent, really helped in terms of defining the area of research and think about what I wanted to formulate in terms of my own research plan.
HOLLOWAY: So, could you give us a few details of some of the work and the new areas that you got into there at Bell Labs?
CHANG: Absolutely. So, one area which I'm currently working on is looking at metal oxides as a dielectric material for various types of microelectronics and optoelectronics applications. And, I started to look at dielectric materials while at Lucent, even though that wasn't part of the project that I was supposed to be working on for my postdoctoral work. (Holloway: Yeah.) So, I collaborated with Marty Green, who was really the pioneer in working on silicon oxynitride material. And, at that time projecting that silicon oxynitride will be replaced eventually by other high dielectric constant materials, we started looking at different type of insulators. (Holloway: Uhm-hmm.) And, in that particular effort I also collaborated with Vincent Donnelly. He's now at the University of Houston, (Holloway: Uhm-hmm.) as a professor in the Chemical Engineering Department, and I really learned a lot more about spectroscopy. And, in collaboration with Mike Steigerwalt I started looking at metal oxides, specifically tantalum pentoxide in terms of the dielectric property, how to electrically characterize these kind of materials. And, those types of experience I did not have (Holloway: Right.) when I was an undergraduate student. So, that has been very valuable.
HOLLOWAY: So, your ensemble of experiences has been very valuable to you then?
CHANG: Yes.
HOLLOWAY: Good. What about your work that you're involved with now at the University of California, Los Angeles? Could you tell us a little bit about that?
CHANG: Yes. So, when I started I decided that I wanted to continue my research in the area of dielectric material synthesis and processes, and taking advantage of what I had learned in my graduate study to combine plasma processing with some of the chemical synthesis technique. (Holloway: Uhm-hmm.) So, recognizing that the dielectric materials that we're interested in for future generations of microelectronics or optoelectronic integrated circuits would have to be of a very thin thickness, on the order of a few nanometers, (Holloway: Uhm-hmm.) the conventional deposition techniques, such as chemical vapor deposition or physical vapor deposition will not meet the requirement or criteria needed for these high quality ultrathin films. So, we started to look at atomic layer deposition, and the essence of this particular process is to design chemical processes so that the reaction is driven by surface functionalization, (Holloway: Uhm-hmm.) in a way that is very similar to self-assembled monolayers. The precursor will react specifically to the functional group on the surface and once those functional groups are consumed they actually will terminate.
HOLLOWAY: So, it's self-assembly in a layer-by-layer technique?
CHANG: Exactly. And then you will have to reactivate a surface by introducing a different chemistry so that you introduce, again, the same functional group to allow the growth of the thin film to proceed. So, it's typical by alternating between two different chemistries, and for a lot of the dielectric material that we're interested in, mainly metal oxides, we'll use one precursor to bring in the metal of interest and then we will use an oxidant to bring in oxygen. So we grow the metal oxygen bonds in a layer-by-layer structure so that we eventually build the material of interest. The unique aspect of this particular process is not only that you can synthesize very high quality ultrathin film but your ability by changing the chemistry to control, for example, the composition of the metal oxide, to control the dopants of the metal oxides, and more specifically control the location of some of these very unique dopants within new material.
HOLLOWAY: This is a fantastic technique. I know that it was first developed, I believe, in Finland?
CHANG: Yes.
HOLLOWAY: And, they used it for development and growth of high dielectric layers with high breakdown strengths.
CHANG: Yes.
HOLLOWAY: I worked in the area of electroluminescent devices (Chang: Uhm-hmm.) for a while, and that's where it really took ahold. Then when the thin gate dielectrics came along and people were looking for a growth technique for doing that, my friend Professor Markku Leskela, (Chang: Yes.) from Helsinki (Chang: Yes. Uhm-hmm.) came over and gave some presentations (Chang: Absolutely.) at AVS.
CHANG: Yes. And AVS has been one of the societies that really promotes atomic layer deposition. The topical ALD conference has been held for five years now, (Holloway: Uhm-hmm.) and it was rotated between the United States, Europe, and Asia, and has really gathered the top researchers in the field from a true international base to discuss what are the challenges and what are the future for extending these particular techniques to various type of applications.
HOLLOWAY: I know that that conference has been going on for, like you say, five years. Are those processes now incorporated into manufacturing of integrated circuits?
CHANG: Okay. So, the true implementation has not started, (Holloway: Uhm-hmm.) but it is projected to be implemented in the forty-five nanometer technology node. And, every main chip manufacturer, starting from Intel to all the other companies, have now decided on the vendor that they wanted to use, (Holloway: Okay.) and started working with them in terms of developing their specific processes that they want. And, a large component of that is to look at what is the exact composition of the film that they are looking for, and then carry out preliminary testing of the electrical performance of these materials, before they finalize on what they really want to do in production because this is a paradigm shift. Once people move away from the thermally grown silicon dioxide based dielectrics there's a lot of interface material issues that control or dictate the electrical performance that needs to be addressed before this material can be fully integrated.
HOLLOWAY: So, how many vendors are there, roughly, for these pieces of equipment, fighting for a foothold.
CHANG: At least a dozen, that is frequently attending the ALD meetings and is very actively promoting their assistance.
HOLLOWAY: Good. Well, this is an exciting time for that effort.
CHANG: Absolutely.
HOLLOWAY: I noticed that your citation for the Peter Mark Award was for pioneering work in the synthesis, processing, and characterization of novel materials for applications in microelectronics and optoelectronics. And so, I understand the application of ALD for thin-gate dielectrics. Are there other applications? And, what are the applications in optoelectronics?
CHANG: So, in optoelectronics, we look at very specific applications where this particular technique can have a huge impact. And, the area that we're looking at is addressing the issue of how to control the spatial distribution of a photoluminescent centers within the wave-guide host material. And the reason why we felt that this particular technique would allow us to succeed is because by looking at literature and we found that this particular device fabrication was done largely through ion implantation, which is a technique that is known to generate defects. It allows the flexibility of introducing large concentrations of dopants, but at the same time we activate the dopants, just like when you are doing dopant activation for integrated circuits, (Holloway: Right.) high temperature annealing processes facilitates the diffusion of these charge centers. And, when they do move and come together and form clusters they lose their charge state, and therefore their photoluminescent properties. So, it's a unique situation where you keep going on, keep increasing the ion implantation dose, but you won't necessarily improve your gain, (Holloway: Uhm-hmm.) just because during the activation process you lose the bulk majority of that. (Holloway: Uhm-hmm.) So, we feel that with the technique that we have looked at so far and then also the chemistry that we have understood in terms of how the reaction will take place, we should be able to control how these optically active centers are introducing to the sample, (Holloway: Uhm-hmm.) normally by using bulky ligands for the metal precursor (Holloway: Uhm-hmm.) and then allows these precursor to deposit and self-saturate on the surface to form a monolayer. (Holloway: Uhm-hmm.) But, because of the bulky ligands, by the time the ligands are removed the metal centers are well separated. And, then if we fill in between those optically active photoluminescent centers that waveguide material through ALD process, and then they will be localized at a position where we designed them to be. And that way, it will not only give us control of the spatial distribution, it will also give us control over how the ions will interact, and how to prevent them from interacting to improve the optical property of these integrated circuit materials.
HOLLOWAY: That's fantastic background, and completely rational logic. Has that actually proven to be true in fact?
CHANG: Yes. So, we have achieved and built erbium doped yttrium oxide samples which are on the order of fifty nanometers (Holloway: Uhm-hmm.) and gives out photoluminescence at room temperature, where the photoluminescent intensity as well as the resolution, meaning that we measure all the Stark splitting, is far better than what has been reported in literature for ion implanted erbium in silica hosts (Holloway: Uhm-hmm.) where in order to get photoluminescence usually the film has to be in the micrometer thickness range and the measurements have to be done at liquid nitrogen temperature. And, you see a broad peak with maybe a shoulder, where you don't see the very well-resolved Stark splitting, because the ions are coming too close and then there's non radiative effects or pathways that compete with the photoluminescence so you don't get the defined features of the erbium three plus intra-4f transition.
HOLLOWAY: It was remarkable the resolution you showed in your presentation yesterday that I was surprised that room temperature vibrations didn't broaden those to the point (Chang: Yes.) where they were not very probable.
CHANG: Because they are all very well isolated, (Holloway: Right.) from one another.
HOLLOWAY: Right.
CHANG: So, the only thing that we're seeing is the splitting of the energy levels due to the crystal field effect, and then we see the exact transitions between those two energy manifolds.
HOLLOWAY: Remarkable. That was a very nice presentation.
CHANG: Thank you.
HOLLOWAY: Where do you see yourself going in the future? You know, you certainly have accomplished quite a lot and you're being recognized for that fact with Peter Mark Award, but what are your plans for the future?
CHANG: I think, for the short term meaning five to seven years, we certainly would like to take the technologies and materials that we have developed so far to the next level, meaning enhance our understanding of what these materials are truly meant for, and then carry them out into real devices to see the actual impact of these materials. (Holloway: Uhm-hmm.) In a longer run, I think in the area of nanotechnology where nanostructures and biology seems to dominate a lot of the research effort, I think I would like to continue to push forward the emphasis of the detailed understanding in the materials front, (Holloway: Uhm-hmm.) especially for the type of inorganic materials that we work with. I truly believe that at some point that the emergence of the inorganic and organic interface will bring us even better advantages in terms of leveraging the unique material properties on both sides. (Holloway: Uhm-hmm.) And, right now the area of materials sort of is separated from the organic chemistry and people have just started to look at how these two aspects can be interfaced. And, we have seen some really exciting development in the area of molecular electronics where signal switches or logic operation is reliant on organic molecules. (Holloway: Right.) And, but there are limitations and the silicon-based technology is very mature in terms of interconnects, interconnection and the density of packing the devices. So, at some point I think these two will merge, will come together, and then really allow us to continue to push the limit in terms of what we can do for computation.
HOLLOWAY: So, you see lots of opportunity in the nanoparticles and the inorganic-organic areas then?
CHANG: Yes.
HOLLOWAY: Is that a strength in your department, or is that just something you'd like to develop on your own?
CHANG: Okay. We certainly would like to recruit more people in this area for our department, and so far we have only two faculty in our department working in the area of the electronic materials, (Holloway: Uhm-hmm.) and we have been working very hard trying to recruit people in this area. And, senior recruit is always hard. Junior recruits, in recent years just because of the strategic planning for the department we have been hiring people in the bio area, (Holloway: Uhm-hmm.) and our department then has recently been changed to Chemical and Biomolecular Engineering Department.
HOLLOWAY: I think that's true around the country, right? [Laugh]
CHANG: Yes. So, we now have a representation, about one-third of our faculty, in the area of biomolecular engineering. (Holloway: Uhm-hmm.) So, I think once that is established we will be able to continue our effort in recruiting people in our area. I believe in critical mass in a particular area where you wanted to really build a solid and strong program.
HOLLOWAY: Right. There is certainly a critical mass effect. (Chang: Uhm-hmm.) That whole area of discussion leads then to my next question and that is, you're certainly an accomplished person that is considered to be young in the science field, and there are lots of other people out there just graduating or still in the university. What advice would you give them in terms of their career development and career paths that you think would be useful for them? Is there a general comment you could make in that area?
CHANG: Sure. I think, well I think a general comment -- and I'll give a more specific comment. A general comment would be, many places like AVS, or some of the federal funding agencies like NSF or ONR, AFOSR, and all these different places, they do recognize young researchers in terms of their research accomplishment. And, in most regards there's an age limitation. (Holloway: Uhm-hmm.) And, students don't realize that when they are graduating from graduate school. They may be in their late twenties or early thirties and they don't really have that much time. And, some people spend a lot of their time thinking about what they want to do and by the time they reach the stage where they will be eligible for these type of awards, unfortunately they have passed that age limitation. (Holloway: Right. Yeah.) So, I think I would truly encourage students who think that their primary interest is in fundamental research continue the momentum from their graduate work. Find a good place to do a postdoc, because I think it really allows you time to think about what you want to do and broaden your research experience. And then, start your research career and then stay really focused.
HOLLOWAY: A quite common age limit is the same as on a Peter Mark Award. (Chang: Yes.) It's thirty-five years old. (Chang: Uhm-hmm.) And, that comes up very quickly after graduate school.
CHANG: Exactly. Yes.
HOLLOWAY: So, that's a very good comment. Do you have other thoughts in that area?
CHANG: The other more specific comment I would like to give would be specifically for graduate students who are women. I think in the past a lot of people have perceived academia as an environment that is not so designed for women, and for a variety of reasons. Now that we have seen at least in the field of chemistry and chemical engineering that a number of female students in our graduate program has exceeded fifty percent in some years, but still the number of female faculty throughout the country or all over the world is still a very small number. (Holloway: Uhm-hmm.) And, I think that is changing, and I do want to encourage students who have the talents and the interest in pursuing this not to be turned away by certain comments or certain perception that they have heard or seen. Just believe in what they can do, and explore the possibility. I do believe that the climate is changing and there are much more opportunities for women to succeed in academia.
HOLLOWAY: Yeah. That's good encouraging news. I know that there's a lot of people that have been focused on that for a while, but certainly much more attention needs to be placed in that area. (Chang: Yes.) Representation in the graduate faculty in minorities and women certainly needs to be improved. (Chang: Uhm-hmm.) Everybody can agree on that. Are there other comments you would like to leave with us today relative to your career, your experiences, your advice for society in general?
CHANG: Well actually, I do have a couple. I think one thing that I do want to mention is that I think AVS is where I started my professional career, (Holloway: Uhm-hmm.) and a lot of my collaboration, which eventually leads to high quality journal publication, started with interactions at the Society, and certainly, other societies too. But, I do believe that research today is different from research twenty years back, and your ability to collaborate with people and the opportunity for you to collaborate with people is much greater compared to what we have seen in the past.
HOLLOWAY: Certainly the tools are much more available today, (Chang: Yes.) for that purpose?
CHANG: And then there are certain instrumentations. For example, when we look at truly nanometer scale type of problems, (Holloway: Uhm-hmm.) the instruments can be hugely expensive (Holloway: Uhm-hmm.) and to imagine one research group that will have all the capability they need to carry out all these studies is just not feasible. So, there could be centers, or there could be one-on-one inter-individual collaboration that can be set up to allow research to be accomplished, while at the same time the collaborators share the credit for doing the work and that'd really help us advance in the area. And so, I think that, this is one of the, I think this is one of the two [Laugh] professional meetings that I come every year. And, I feel that this is a very important component of that, not only that myself and my students get a chance to present all the work at the Society, but at the same time we get feedback, we discover what other people are working on, and we find new areas or opportunities to collaborate. And, much of this would not happen if we just try to sit in our office and read the proceedings or browse through the abstracts. It think that the level of interaction is truly different. (Holloway: Right.) So, I think that's one of the very unique aspects. And, AVS has long been known to recognize student accomplishment. (Holloway: Uhm-hmm.) And, I think one of my, one of the deciding factor in my choosing academia as the career path has a lot to do with receiving the Coburn and Winters Award from the Plasma Science and Technology Division as a graduate student. And, over the years I've continued to participate in that division, and I get to know a lot more people, and the collegial environment as well as the focus of the group in terms of building the program is really what attracts me and a lot of people to continue to come back year after year to give back to the society.
HOLLOWAY: Well, those are fantastic comments. It is really literally true that outreach is a requirement for faculty and students now to build the multi-investigator programs that are essential for making (Chang: Uhm-hmm.) good progress. And the comments about the society, I believe, are quite accurate as well. So, we are grateful for those comments and observations, and personal experience, in fact, (Chang: Yes. Absolutely.) that demonstrate so many accomplishments. Good. Are there other things that you would like to share with us this morning?
CHANG: I think one other thing that I do want to mention is ability of faculty, I think. What differentiates a faculty from a researcher in a national laboratory or in an industrial laboratory is the ability to work with students. (Holloway: Uhm-hmm.) And, that part has been a true gift to me over the past six years. I feel really privileged to work with students in their prime time. We look at undergraduate students, they range from, you know, the late teens to early twenties, and then for graduate students largely in their twenties. And, you must spend time with them, especially with a graduate student, maybe four or five years. And, to watch them to develop and grow, and contribute, and eventually learn something from them, I think, is an invaluable experience. And to me that is very unique for this particular profession, because most of the time if you work, if you stay at the workplace for say twenty-some years, your coworkers will age with you. But, in this business, [Laugh] no. You age, but the people that you work with stay young.
HOLLOWAY: But, that keeps you young too, right? [Laugh]
CHANG: Exactly. So, I think that's truly, that's truly one unique aspect of being a faculty and doing research in academia. (Holloway: Uhm-hmm.) And, I have the pleasure to work with really outstanding students, both graduate and undergraduate students and I really do believe that this is what's... I truly believe that I made a right decision and this is what motivates me to continue to do my work.
HOLLOWAY: It sounds like you made the right decision, and made the right decision for the right reason as well. I frequently tell people there's only one good reason to be at a university and that's if you enjoy working with and mentoring and educating students.
CHANG: Yes.
HOLLOWAY: And learning from students.
CHANG: Absolutely.
HOLLOWAY: I like that aspect of your comment too, because there's never a student that you encounter that you don't learn something from.
CHANG: Exactly. Yes.
HOLLOWAY: So, that's wonderful. Okay, anything else?
CHANG: I think that will probably cover most of what I have.
HOLLOWAY: Well, good.
CHANG: And, I do want to thank the AVS Society again for this recognition.
HOLLOWAY: It's a pleasure to recognize excellence and the Society has worked very hard at accomplishing that. And, in your case I'm absolutely convinced that we've succeeded.
CHANG: Thank you very much.
HOLLOWAY: You're welcome.