Awardee Interviews | Mark C. Hersam - 2006 Peter Mark Award - Interview

Mark C. Hersam

Oral History Interview

 

Interviewed by Paul Holloway 2006
 
HOLLOWAY: Good afternoon. My name is Paul Holloway. I am a member of the AVS History Committee. We are here today, Tuesday, the 14th of November, in San Francisco at the 53rd Annual Symposium of the AVS to interview Dr. Mark C. Hersam from Northwestern University, the 2006 Peter Mark Memorial Award Winner. Mark's citation for the Peter Mark Award reads "for outstanding contributions to the development of silicon-based molecular electronics". So Mark, it is a pleasure to have you here today. Thanks very much for agreeing to do this interview and congratulations on the award.

HERSAM: Thank you very much.

HOLLOWAY: Just to get us started, how about giving us a little bit of a background on yourself?

HERSAM: Sure. I grew up in Downers Grove, Illinois, which is a suburb of Chicago very close to Argonne National Lab. My mother is an English teacher and my father works for Spiegel Corporation. Neither of them are scientists, and so maybe it is a bit surprising that I ended up in this field. I think that is in a large part due to the local outreach programs in the Chicago area from places like Argonne National Laboratory.

HOLLOWAY: Is that right?

HERSAM: Yes.

HOLLOWAY: Did you participate in those as a student?

HERSAM: Yes. When I was a high school student I would go to Argonne and participate in the outreach programs.

HOLLOWAY: So that got you interested in this?

HERSAM: That definitely contributed to my interest in science.

HOLLOWAY: Can you tell us a little bit about some of the projects that you conducted or participated in when you were a high school student?

HERSAM: Yes. At Argonne they are very strongly involved in X-ray measurements.

HOLLOWAY: Right.

HERSAM: Also advanced microscopy techniques. And so that was the topic of my participation in the outreach programs. They taught us about X-rays, how they can be utilized to study the atomic structure of matter, and also introduced us to advanced microscopy techniques such as electron microscopy.

HOLLOWAY: So did you have your name on a published paper at all as a high school student?

HERSAM: No, not quite.

HOLLOWAY: Well, that's a noble objective but you probably only achieve that only one out of every hundred students or so.

HERSAM: Yes, probably. But it did achieve the objective of getting me interested in science - someone who really had not had a real exposure to it before that.

HOLLOWAY: Good. So then you went on from high school to -?

HERSAM: Yes. And then I went on to the University of Illinois Urbana-Champaign.

HOLLOWAY: Which department?

HERSAM: I was in the Electrical Engineering Department and earned a bachelor's degree there. During my undergraduate days I performed research in the laboratories of two professors. One was Professor David Ruzic, who was in the Nuclear Engineering Department at the University of Illinois and a very active member of the AVS. In fact, it was Professor Ruzic who first allowed me to go to an AVS conference as an undergraduate.

HOLLOWAY: Was that in the local area or -?

HERSAM: It was in Minneapolis. I drove my car there.

HOLLOWAY: I remember the first time I attended a conference, I drove my car to it as well.

HERSAM: Yes, so that was my first real exposure to AVS and to the large-scale conference experience. I will always remember that, and I have always felt AVS to be my home Society, probably as a result of those early experiences.

HOLLOWAY: That's good. So you enthusiastically applaud our efforts to encourage the involvement of students with the undergraduate and graduate level in the AVS.

HERSAM: Absolutely, yes.

HOLLOWAY: Good. Well we've worked hard at doing that, so I'm glad to hear it paid off.

HERSAM: Yes. I'm an example, and I think there are more of us. The other faculty advisor that I had for undergraduate research was Professor Joseph Lyding, who is also an AVS Fellow and active member of the Society. I performed research in his lab, and he is in the Electrical Engineering Department.

HOLLOWAY: Good.

HERSAM: So after the University of Illinois, in between that and my graduate study, I spent a few months at Argonne National Laboratory. So, I returned there and was an intern performing research on surface acoustic-wave-based sensing.

HOLLOWAY: Did you work for anybody in particular there at Argonne?

HERSAM: My direct advisor was Sanjay Ahuja, and his advisor was Constantine Raptis who was a relatively high-level individual in the Energy Technology Division at Argonne National Lab. Following that internship I then entered graduate school. I first attended the University of Cambridge in the UK for a master's degree in microelectronic engineering and semiconductor physics.

HOLLOWAY: How in the world did you ever get hooked up with the University of Cambridge for your master's degree?

HERSAM: I was fortunate to win the Marshall Scholarship, the British Marshall Scholarship.

HOLLOWAY: Congratulations.

HERSAM: Thank you. And that of course includes a graduate research and educational experience in the UK.

HOLLOWAY: Did you apply for that on your own or did you have encouragement to apply for that?

HERSAM: I was encouraged, and -

HOLLOWAY: By your mentors?

HERSAM: Yes, they certainly were very helpful in the process, helping me identify opportunities. This was one of them.

HOLLOWAY: Right. That's a critical role I believe that the mentors must play, is to encourage and make people aware of opportunities, because otherwise how do you become aware of them and how do you know to participate?

HERSAM: Exactly. They were also helpful in identifying faculty advisors in the UK that would be suitable and consistent with my interests, which were in the area of nanoelectronics. And so in particular Professor Lyding identified Professor Mark Welland at the University of Cambridge as a suitable faculty advisor and helped mediate that initial contact and the setup of my degree and research program with him.

HOLLOWAY: So networking has been very important for you all the way through.

HERSAM: Absolutely.

HOLLOWAY: That's a critical aspect of participating in the AVS and other professional societies, that the students need to appreciate and develop an understanding in being able to use in fact to their strong advantage.

HERSAM: Right.

HOLLOWAY: Good.

HERSAM: So that was a clear example. Myself, an undergraduate in Illinois, really didn't have a sense of what was happening on the larger stage, but of course my faculty advisors could point me in the right direction.

HOLLOWAY: Good. So the nanoelectronics and Cambridge. What did that boil down to then?

HERSAM: What that boiled down to was they had a project from the EU to look at gold nanowires. Ultimately the objective was to understand how much current could be passed through small interconnects in integrated circuits and try to understand how to prolong the lifetime of interconnects.

HOLLOWAY: Was this looking at the mechanisms of electromigration then?

HERSAM: Exactly.

HOLLOWAY: Yeah, okay.

HERSAM: Exactly. It was trying to understand electromigration better and the approach was to utilize scanning probe microscopy, in particular conductive atomic force microscopy, to spatially map the electrostatic potential distribution along a gold nanowire while it was operating and in that way observe the potential as it evolved under the application of electrical stress to identify if there were hotspots, which would ultimately lead to failure.

HOLLOWAY: Yeah. So really electromigration is normally a combination of thermal migration plus electromigration.

HERSAM: That's right.

HOLLOWAY: And so trying to characterize the parameters for that is very difficult.

HERSAM: Exactly.

HOLLOWAY: So that's remarkable. I'm glad. I hope it came out successful.

HERSAM: Well, we successfully developed this new technique, which allowed us to achieve previously unprecedented spatial resolution, so we could really map out what was happening at the nanometer length scale. That provided some insight into the mechanism and allowed us to propose some means of prolonging the lifetime of those interconnects.

HOLLOWAY: So how did you make the nanowires in the first place?

HERSAM: They were patterned by electron beam lithography.

HOLLOWAY: So it was down on a silicon substrate or something like that?

HERSAM: Silicon dioxide, yeah, that's right. And the diameter or the width of these rectangular cross-sectional wires was about 60 nanometers. The thickness was about 20 nanometers and the length was about 1 micron.

HOLLOWAY: Yeah. So you were using electron beam lithography then for that.

HERSAM: That's right. I was collaborating with a postdoc in Mark Welland's group. He was the e-beam lithography expert. I participated peripherally in the fabrication but more directly in the characterization.

HOLLOWAY: So you got your master's degree then from Cambridge?

HERSAM: That's correct.

HOLLOWAY: Good for you.

HERSAM: And then I returned to the University of Illinois Urbana-Champaign to pursue a Ph.D. in electrical engineering. That research was accomplished in the Beckman Institute in Urbana-Champaign, which is an interdisciplinary research center on the University of Illinois campus. The Beckman Institute was the primary reason I wanted to return to the University of Illinois. It's a very dynamic and diverse environment, and I felt that it would allow me to learn as much as possible during my Ph.D.

HOLLOWAY: So what was the subject of your dissertation for the Ph.D.?

HERSAM: For the Ph.D. I was looking at hydrogen on silicon with ultra-high vacuum scanning tunneling microscopy.

HOLLOWAY: Right down the AVS line of interest then.

HERSAM: Yes, absolutely.

HOLLOWAY: Good.

HERSAM: And trying to understand the process of desorption of hydrogen from silicon using the STM tip as a localized electron beam to inject charge into the silicon-hydrogen bond. And to control that desorption process down to the single atom level. So it was a form of nanolithography.

HOLLOWAY: So the desorption was off of a room-temperature surface or you heated the substrate a little bit?

HERSAM: In my experiment it was all done at room temperature. That's right.

HOLLOWAY: That's an interesting experiment on a really important subject, and so I'm sure that you contributed to the understanding in the field.

HERSAM: Yes. It was very relevant not only from a fundamental perspective but also for applied technology. Hydrogen desorption is critical in microelectronic devices. In particular, the desorption of hydrogen from the silicon-silicon dioxide interface ultimately leads to shifts in threshold voltages in conventional field effect transistors and ultimately the failure of integrated circuits. So understanding that process better had impact on that applied technology as well.

HOLLOWAY: So who was your major professor then there at the University of Illinois?

HERSAM: My direct advisor was Professor Joseph Lyding, so I went back and reinitiated that line of research.

HOLLOWAY: It comes full circle here.

HERSAM: It did, yes.

HOLLOWAY: It gives you a recommendation to go to Cambridge and get educated and you come back and help it out [correct 3 words?].

HERSAM: That worked out for everybody.

HOLLOWAY: You had another mentor there at the University of Illinois, or two, as well.

HERSAM: Yes. So I had previously been working with Professor David Ruzic when I was an undergraduate, and I kept in touch with him and still see him at AVS meetings every year.

HOLLOWAY: What is Professor Lyding?

HERSAM: Professor Lyding was my primary advisor.

HOLLOWAY: Were there other people there at the University of Illinois during your Ph.D. career that were particularly helpful for you?

HERSAM: Yes. I would say Professor Karl Hess, who was also in the Electrical Engineering and Physics Departments. He is a theoretician who worked closely with Professor Lyding and helped explain some of our experimental results. He was a very important player in my development. Also Professor Jeff Moore, who was in the Chemistry Department. This project had a component of looking at how we could utilize this lithographic approach as a means of templating the assembly of organic molecules onto silicon. From Jeff Moore I learned organic chemistry, and that has been a very important part of my subsequent research.

HOLLOWAY: What about the Beckman Institute? Were all of those located or colocated in the Beckman Institute?

HERSAM: That's right.

HOLLOWAY: And so the interaction that you could from that colocation was very important then.

HERSAM: That's exactly right, yes.

HOLLOWAY: Were there other people that were colocated there that were peripheral to your studies then too?

HERSAM: There were. There were other faculty members who I work with much more closely now that I have left the University of Illinois, but not while I was there.

HOLLOWAY: So you knew their capabilities and expertise.

HERSAM: Yes, including Professor Steve Sligar who is in the Biochemistry Department and Professor Sam Stupp who incidentally is now at Northwestern University where I am currently located. When I was a graduate student, I shared an office with his graduate students, so I knew what the Stupp group was doing. When I came to Northwestern, I was in a good position to initiate a collaboration with them.

HOLLOWAY: That raises an interesting question that I would like to see what you think about, and that is, we always think of education of a student as being a professor-student relationship. But there is much learning that goes on between the students, and I was wondering if you might think about that and comment about the interactions with your fellow graduate students.

HERSAM: I absolutely agree with that, and that is what I think the Beckman Institute was particularly good at doing. It was not just the professors who talked to one another. They certainly did, but because we were all colocated and shared office space, just by chance interactions, you would talk to these other graduate students. To another graduate student you can ask more detailed questions and stupid questions. You actually learn a lot from questions that you would never be comfortable asking a professor about.

HOLLOWAY: That was a stupid question, but some of them when you think about them sound stupid but are very insightfull.

HERSAM: Exactly. Plus, graduate students, when they are sharing office space, have a lot of time to interact. The amount of time a professor has is finite, and so just having more time to interact with people from other areas enables you to learn more and learn how to do research in an interdisciplinary way.

HOLLOWAY: How about colocation of equipment besides colocation of people? Was there an advantage with colocation of equipment as well?

HERSAM: Absolutely. Yes. And there was of course the equipment in the individual professors' labs and since they were right down the hall you could gain access to those pieces of equipment. There were also public facilities in the Beckman Institute, which were very useful. And again, you'd run into people down there who were working on at least the same experimental approach, maybe on a completely different system but you could ask questions and that cross-fertilization was very important.

HOLLOWAY: Just to establish a timeline, what year did you go back to the University of Illinois and start your Ph.D. and then finish?

HERSAM: I arrived in the fall of 1997.

HOLLOWAY: Back from Cambridge.

HERSAM: Back from Cambridge. And since I had a master's degree I took approximately three years for my Ph.D. I completed my Ph.D. in the summer of 2000.

HOLLOWAY: You got your bachelor's and your Ph.D. from the same institution.

HERSAM: Right.

HOLLOWAY: I was wondering if in hindsight whether you thought that was a good experience, a valuable experience, or something that you would like to comment on.

HERSAM: Yes. I would say if I had gone from undergraduate to Ph.D. without having gone anywhere else, I probably wouldn't recommend that. But because I had gone to Argonne and then to Cambridge, I had seen a couple of other places and I could recognize what specifically at the University of Illinois was going to be advantageous for me: the Beckman Institute. While it's certainly part of the same university, it's kind of a unique place in and of itself. I don't think I would have returned to just the university. I would not have just joined a random research group in the Electrical Engineering Department. It was really the Beckman, which drew me back. The other thing which Professor Lyding offered to me when I contacted him from Cambridge was an opportunity to have an extended stay at one of his collaborator's labs at IBM T. J. Watson Research Center. That was the lab of Dr. Phaedon Avouris, who was another important mentor of mine. So during my Ph.D. I spent about six months in his laboratory. So even though I was getting my Ph.D. from the University of Illinois, I had this extended experience at IBM. I viewed that as another great opportunity – which I felt I could take advantage of because I knew ProfessorLyding already and I understood that he would see the value in that experience in terms of diversifying my experience.

HOLLOWAY: So Avouris is well known for studies of carbon nanotube devices.

HERSAM: Correct.

HOLLOWAY: And you were participating with that I presume.

HERSAM: That's right. I was working on multiwall carbon nanotubes, trying to understand how they could be utilized as interconnects in integrated circuits. So, it was similar in a sense to my master's research where I was looking at gold nanowires; here I was looking at multiwall carbon nanotubes, pushing them to their limit in terms of current-carrying capacity and trying to understand how they failed. And there is a quite interesting difference. With metallic nanowires you tend to see a continuous decrease in current flow ultimately leading to failure. In the carbon nanotubes, on the other hand, you see that the current drops in a stepwise manner as you reach failure. We concluded that this was due to the fact that most of the current in a multiwall carbon nanotube is carried in the outermost shell of that nanotube. So when that shell fails you have an alternative path, and that is through the next innermost shell. It comes at a slight cost because the coupling between the shells is not particularly good, so you get a drop in current flow due to an increase in resistance. But it's a very controlled process and it occurs on a relatively long timescale. So if you have a feedback loop running, you can terminate that process at any point, allowing you to narrow the multiwall nanotube down one shell at a time. That ended up being a productive path of research which Avoris then continued after I left his group.

HOLLOWAY: Were there other people in the group that you worked with or primarily Avoris?

HERSAM: I worked with Avouris and also Dr. Richard Martel, who was another staff scientist at IBM who had been working with Dr. Avouris for quite some time. He was my direct contact when I had questions.

HOLLOWAY: Right.

HERSAM: And then when I had bigger picture questions I would talk to Dr. Avouris.

HOLLOWAY: Can you give us a perspective on a student as a graduate student working in an industrial laboratory versus in the Beckman Institute? Is there similarities or differences?

HERSAM: I would say the most obvious difference for me was IBM had what seemed to be a much larger number of resources than the university. So I never felt like there was a question about budget or access to instrumentation. T.J. Watson Research Center really had almost unlimited resources in terms of experimental equipment and access to such equipment. The difference was that at IBM the age distribution was quite different. At the university you have a very large number of students and then a few faculty whereas at IBM it was opposite; there was a very few number of students and a large number of senior people. And so I guess the energy of the places are different; at the university there are a lot of young people working really hard to do things but probably don't know as much, whereas at IBM you find people who knew a lot but maybe didn't have the same sense of urgency that you felt at the university among the students.

HOLLOWAY: So those were valuable experiences then.

HERSAM: Yes, absolutely. And it really allowed me to have a good sense of what I wanted to do when I graduated, because I had seen research in industry and at the National Lab when I was at Argonne.

HOLLOWAY: So did that mean that you went directly from the University of Illinois to academia?

HERSAM: That's correct.

HOLLOWAY: Did you do a postdoc or just straight to a faculty position?

HERSAM: I went straight to being an assistant professor at Northwestern University.

HOLLOWAY: And that's in which department?

HERSAM: In the Department of Materials Science and Engineering, and that's where I am today.

HOLLOWAY: Well good for you. That's an excellent place to be. Material Science is my home department, so it's near and dear to my heart.

HERSAM: Yes.

HOLLOWAY: So tell us about what you, as a young professor coming into a new position,are working now on, what research areas, and how different are they from what you did your dissertation in?

HERSAM: Right. So in a sense it changed for me, because I had degrees in Electrical Engineering and Physics, but no degrees in Materials Science and Engineering, yet I ended up in a Materials Science and Engineering Department. I think that was in large part influenced by the Beckman Institute and the interdisciplinary training that I received. So there was the possibility of looking outside of electrical engineering then to be a faculty member. When I joined the Materials Science and Engineering Department, I viewed it as a great opportunity to take what I had learned and really focus on the materials aspects of the problems that I had been working on. My interests when I arrived were still in the area of nanoelectronics, and what I saw during my education was the relentless pursuit of miniaturization of the field effect transistor. What you were beginning to see was that the problems weren't really with the lithography, though of course lithography will always be an issue for that industry. But more the issues were fundamental materials problems.

HOLLOWAY: Right.

HERSAM: You saw for example that aluminum was abandoned for copper as the interconnect material due to electromigration. There were grumblings about the thickness of the silicon dioxide getting too thin, tunneling being a problem, and as a result the pursuit of high-k gate dielectrics. When you do that then the top silicon gate material had to be changed to metal gate materials. In the field dielectrics, the desire was to have low-k materials. So just looking at the future of electronics, it appeared to be materials issues were fundamental to furthering progress. And so I felt that I would really like to be in a Materials Science Department and focus on alternative or more exotic materials for electronics. And so that led me to think even more exotically toward organic materials. And that is something which I had gotten a taste of during my Ph.D. but wanted to pursue more seriously as a faculty member.

HOLLOWAY: When you say organic do you mean carbon base or small molecule oligomer-polymer type of materials?

HERSAM: We look at small molecule hydrocarbons. Also we look at some polymer or polyelectrolytes, molecules like DNA. So that's what I mean by organic. We do some work with carbon nanotubes, and that's a result in part of my training with Phaedon Avouris at IBM. But I view a carbon nanotube to be largely an inorganic material in terms of how it behaves. We then add to that. We coat the nanotube with organic molecules, either polymers or biomolecules such as DNA. The hope is that we don't want to use organic molecules to replace or compete with conventional microelectronic materials such as silicon.

HOLLOWAY: Right.

HERSAM: Rather to add it on top of that platform to hopefully add additional value, for example the chemical reactivity of organic molecules can be very selective and therefore useful in sensing for example.

HOLLOWAY: That's an interesting area. It has potential applications for connecting the human mind to the electronic device in the far future.

HERSAM: That's right.

HOLLOWAY: So that certainly has to be one of the top priority very long-range goals for everyone

HERSAM: Yes. That's a vision I have had for a while and I think it will take a lot longer to get there, but a great example of that would be retinal prosthesis, i.e. giving site to the blind. Well, we all know that there are light detectors which use semiconductor materials.

HOLLOWAY: Yes; e.g. artificial eyes.

HERSAM: Yes. So in order to get that electrical signal which comes out of a photodiode, for example, to interact with the human body you need to have some interface between that microelectronic device and the optic nerve. And so that's obviously an inorganic-organic interface which has to be understood down to the molecular level to do it effectively. And so that's a long-term objective of our lab. We're slowly but surely making progress towards that goal. 

HOLLOWAY: So what sort of actual materials are you looking at? Is it silicon IC materials with small molecules on it and looking at charge transport across that or something like that?

HERSAM: That's right, yes. An important area for us is to try and understand how current flows through a metal-molecule-semiconductor junction. This is relevant to the field of molecular electronics. And if you look at the field of molecular electronics almost all of the research is done on gold surfaces with so-called thiol molecules and then a gold-type contact.

HOLLOWAY: Right.

HERSAM: And that's a very promising approach, because gold is relatively inert and forming ordered monolayers with thiol molecules is relatively easy to do. But we felt that looking at a silicon substrate could have some significant advantages over gold, in particular since silicon is directly below carbon in the periodic table. Therefore, the binding chemistry of organic molecules to silicon is very similar to binding chemistry between organic molecules themselves. So you can have strong covalent interactions which give you the possibility of very stable contacts. Since silicon is a semiconductor, it has other advantages. You can tailor the majority charge carrier via doping, which is obviously not an option in gold or any metal. Finally there is a band gap which is present, and that band gap gives you some other possibilities for realizing novel charge transport phenomena. And, of course, it is a clear winner in the microelectronics industry, so we felt that working directly on silicon would have at least a possibility of being transferable to the marketplace.

HOLLOWAY: What do you see in terms of the future? How far away is a silicon organic material interface that is functional in a practical device that somebody can go to Radio Shack and buy?

HERSAM: Yes. I think down to the single-molecule level it's a long way off, but if you're talking about thin films or monolayers of organic molecules, for example if you look at the fields of organic electronics or organic light-emitting diodes, you see that these materials are beginning to be used in current technology. For example, cell phone displays are now utilizing organic light-emitting diodes. So I think that macroscopic organic materials are already beginning to have an impact. Can we get all the way down to the single-molecule level? With the scanning tunneling microscope, which is a tool in my lab, we can do that today, but to make one billion of those devices working together is a very difficult problem – probably decades in the future.

HOLLOWAY: Let me turn your attention a little bit away from the technical side of your program and ask you a question that I know that other students that are coming through the Society would be interested in understanding, and that is, you are now a fresh Ph.D. graduate going to Northwestern University. How do you know what are the critical aspects that you need to pay careful attention to to get your program started and get your funding started and get the graduate students in the door and actually be successful – and receive the Peter Mark Award, for example.

HERSAM: Yes. So, I made a decision when I started that I was going to focus my attention initially on recruiting the best students that I could. It was clear to me that, with the expectations on faculty members today – which are quite high in terms of funding, teaching, and service – that a professor can't do all of that and be in the lab on the front lines running all the experiments. You need to have an effective team of graduate students who can execute the ideas that the professor has.

HOLLOWAY: Right.

[end of Tape 1, Side A]
[beginning of Tape 1, Side B]

HERSAM: So I focused on recruiting. That was the first step. The second step was to assemble the resources that I would need to enable those students to be successful. And that included setting up the right type of equipment and of course raising funds to support that equipment and the research that we wanted to perform. And so in that first year I spent a lot of time writing proposals, trying to establish a solid base of funding. Once the team was in place and the resources were in place, then I tried to create an environment in the research group which was collaborative and really a team environment where students would work in a collaborative way to make progress – not only within my group but with other groups. We felt that collaboration was critical to being successful on the interdisciplinary problems that we were working on. With the team in place and the resources in place, we then executed our plans and I guess the rest is history.

HOLLOWAY: As they say, good. It takes a lot of time and energy and dedication to be successful in a program like that, and you are certainly to be complimented for the success and the basis for the award. So where do you see yourself going in the future?

HERSAM: Well, we talked a little bit about long-term vision. The interface, for example, between microelectronics and the human body is one which I am now beginning to think about more seriously. And we are trying to think of how we can take what we have learned thus far and apply it more and more closely to real biological systems. And one technique which has been very important in my lab is scanning probe microscopy. It's a technique which is useful and been largely applied to inorganic materials and now more and more to the organic-inorganic interface, but not as extensively to pure biological systems. So we're beginning to think of how we could exploit the spatial resolution of scanning probe microscopy to understand important problems in biology. And so when thinking about this problem I opened up a biochemistry textbook and just browsed through it. And if you look through a biochemistry textbook you will see a lot of cartoons – a lot of cartoons of cell membranes and proteins, and there's not a lot of real space microscopic evidence for what these structures look like – for example, what is the spatial distribution of ion channels on a cell membrane surface.

HOLLOWAY: I agree with you 100%.

HERSAM: And so now we're beginning to think, "How can we utilize this very successful microscopy technique which has been applied in the physical sciences to the life sciences?" And that's a growth area in my research group. Our initial objective is to try to apply the techniques of conductive atomic force microscopy to spatially mapping the location and the behavior of ion channels in living cells. And so that's a project which we were recently funded to begin work on and a couple students are now pursuing that seriously.

HOLLOWAY: That's a great idea. I've often remarked to my students in the nanostructures area that it's time to go beyond the cartoons.

HERSAM: Yes.

HOLLOWAY: We really need to have some real solid evidence that what people are drawing up there is real. It's easy to draw a good cartoon, but it's hard to prove that that cartoon is accurate and representative of what you are trying to study.

HERSAM: Yes. Right. So that's definitely a very promising future direction for us.

HOLLOWAY: Good. Any other comments you would like to make about mentors or people that you have worked with along the way, for example some of your graduate students that you are currently working with?

HERSAM: Yes. So again, I would like to extend my thanks to my mentors. I mentioned them before, Professor Ruzic and Professor Lyding, at the University of Illinois. Also Professor Welland at the University of Cambridge and Dr. Avouris at IBM. I also would like to thank my graduate students, my postdocs and also undergraduate students who have enabled my research group to accomplish what it has accomplished thus far.

HOLLOWAY: For mentoring there at Northwestern, have you had the pleasure of being mentored by one of the senior faculty members in the department?

HERSAM: Yes. Northwestern has a very nice program. When you first arrive, you are actually assigned to two faculty mentors. Professor John Torkelson was one of those mentors and Professor Michael Bedzyk was the other mentor. And it's amazing how large of an impact they have when you first start, because I think when you enter a new place you are somewhat naïve. You are very enthusiastic and want to do things, but you really don't understand the lay of the land, how to get things done, which political pitfalls to avoid. They were very helpful in helping me navigate the institution of Northwestern University: understand where I should be focusing my effort; time management is obviously important in all careers, but especially important in academia where there are so many things pulling on your time. They were helpful in identifying where I should be focusing my efforts, so I also thank them for their contributions.

HOLLOWAY: Good. Is there anything else that you would like to discuss for the interview?

HERSAM: I think that's about it for me.

HOLLOWAY: Congratulations again on the Peter Mark Award, and thank you again for being willing to participate. The interview has been very enjoyable for me and I have learned a lot about this research area. Thanks again.

HERSAM: Yes, my pleasure.


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