Episode 11: Solar Cells and Semiconductors with Professor Vikram Dalal

In this episode, our guest is Professor Vikram Dalal from the Department of Electrical and Computer Engineering (ECpE) at Iowa State University (ISU). Here, we talk about the latest trends in the semiconductor industry, both within the integrated circuit (IC) and solar cell technologies. We also learn about the capabilities available at the ISU Microelectronics Research Center (MRC) to design and fabricate our own chips, along with courses and career paths available for students interested in this field.  This episode was conceptualized, recorded, edited, and produced by Santosh Pandey from the ECpE Department of Iowa State University. The transcript was prepared and edited by Santosh Pandey from the ISU ECpE Department. The communications and digital hosting was handled by Kristin Clague from the ISU ECpE Department. The music was provided by Lesfm from Pixabay (Track Title: Inspiring Inspiration (IG Version 30s)). 

Transcript

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Welcome to our ECpE podcast series where we talk about exciting activities within our department. I'm your host Santosh Pandey. Our guest today is Professor Vikram Dalal from the Department of Electrical and Computer Engineering at Iowa State University. Dr. Dalal, thank you for joining us in this episode. Today, we want to talk about the latest trends in semiconductor industry and what resources are available for our students to build a career in this field. To start with, could you tell us briefly about your research and facilities available at the Microelectronics Research Center. My research is focused on discovering and working with new semiconducting materials. Semiconducting materials are ubiquitous. Not only are they used in computer chips, but they are also used in all kinds of sensors, they are used in displays, and they are also used extensively for solar energy conversion. So, the research that I do involves discovering new semiconductor materials with unique properties. In particular, I work on optoelectronic materials, materials that convert light into electricity or that can be used to convert electricity into light. So, it is a very exciting field. All are light-emitting diodes are based on optoelectronic materials, all of the solar cell devices, all of the lasers, everything else. All the optical devices are based on semiconductor materials. And one always needs to keep working on new material systems in order to lower the cost and to improve the performance. So, that is my basic research field. And in terms of facilities, we have an excellent facility for making a variety of semiconductors, particularly thin-film semiconductors, thin films of silicon, other material germanium. And also we recently acquired a facility for doing Gallium Nitride, Gallium Oxide type, large bandgap semiconductors which are very useful for high-frequency devices and more importantly for high power devices. For example, for switching large voltages. So we have a new faculty member who works in that. The facilities include a very thorough fabrication facility for silicon. Silicon chips are the kind of chips that are used in computers, and the students learn how to, starting with the silicon wafer, how to make the fundamental device called the MOSFET device. In this material, they go through every single step of fabrication, and they go through all of the characterization and analysis, and measurement of the devices. So, we also have a very thorough characterization lab, both electronic characterization lab and also an optical characterization lab. How can our students have access to the facilities and equipment in the Microelectronics Research Center (MRC)? Very simple. By asking, if they are interested and they are in the appropriate fields - Physics, Chemistry, Material Science, Electrical Engineering, Chemical Engineering, Mechanical Engineering, etc. All they have to do is come to MRC and sign up and then we give them the appropriate safety training and then we train them on the specific equipment that they will be using for their individual research projects. They can also learn the basic technology by taking an important course that we teach called Semiconductor Fabrication. It is EE 432 and that course provides them with all of the training needed to be able to use most of the lab equipment. As you can imagine, the lab equipment is very expensive and it's also dangerous. The appropriate safety procedures have to be followed. So we train the students in appropriate safety procedures and they know how to use the different lab equipment, so that they can produce the devices that they want and the research that they want to do. In recent years we have seen there's a tremendous demand for consumer electronics, Renewable Energy, Autonomous Vehicles and Data Centers. In this context, why is the knowledge of semiconductors all the more important for our students? Every one of the devices you mentioned, every one of the technologies you mentioned relies on semiconductors. The semiconductors are the working brain for which virtually all of these devices. And so if you understand how semiconductors work, how to fabricate the semiconductors, then you'll do very well in being able to develop more advanced technologies in each of these fields. Through your career, you have collaborated with several microelectronics Could you name some companies in this field and what kind of job opportunities are available to our graduating students in these companies. Sure. The job opportunities exist from the Bachelor's level, all the way to the Ph.D. level. So Bachelor's, Master's and Ph.D's. And the salaries are very attractive. Also, the companies provide internships. If you are a student with a good GPA and show enthusiasm and interest in the field, you are very likely to get internship with these companies while you are an undergraduate or a graduate student. The companies that I work with mostly are Intel, mainly in Portland, Oregon but also in some of my students have gone on to their facility in Albuquerque New Mexico and Chandler, Arizona just outside of Phoenix. Then the other company that I work very closely with is Micron Technology, which is the world's largest manufacturer of semiconductor memories. You know, your flash drives. So Micron makes them. Their headquarter's in Boise, Idaho but their facilities in Virginia, their facilities in Utah. They have research labs in California. And they also have manufacturing in, I think in Taiwan. Certainly, in Japan and Singapore. And I have students who have gone on to Singapore. I have students who have gone on to Utah, and lots of students who have gone on to Boise, Idaho which is where their main research lab is. The other companies that I work with, that my students goto is Qualcomm in San Diego, Applied Materials which is in Silicon Valley and then, of course, Apple. I guess those are the major companies, major large companies that I work with. And of course, companies like Honeywell and what not in Minneapolis. So, the Microelectronics Research Center attracts students from a wide variety of majors, whether it does electrical engineering, physics chemistry or material science. Could you elaborate on this? Yes. This is an interdisciplinary field. It's not only electrical engineers. We need people who understand materials. We need people who can process materials to people who understand devices. People who can fabricate devices into useful circuits or the entire System on a Chip. We need people who can make sensors for agriculture, for example smart agriculture is very important. And so, we have people here who are working on making sensors for smart agriculture, so we can minimize the use of fertilizers and pesticides and water in plants. So, we have people working in all these areas. And physics, material science, chemistry, electrical engineering, mechanical engineering provide the appropriate So it's very important to have a group that includes, a group of students which includes people from all this areas. That's great. You have witnessed the advances in solar energy over the past few decades. Could you tell some of the revolutions that have happened within this field? And who are the leading solar technology companies today? Yes. When I started in solar energy that was back in 1973. A long time ago. At that time, the cost of a solar cell was greater than hundred dollars a watt. Probably more like two or three hundred dollars a watt, in terms of capital cost. Today the cost of solar cell is 50 cents a watt. Price has gone down by a factor of 500 in the last 50 years. And that has been made possible by improvements in technology, and by mass production. When I started, solar cells would hardly, you know, they were used in satellites and they were used in Remote Relay stations for relaying communication information. But outside of that, nobody was putting solar cells on the roof. Today approximately hundred gigawatts. Gigawatt is 1000 megawatts. A typical nuclear power plant is a gigawatt. A typical large coal burning power plant is a gigawatt. Today, over 100 gigawatts per year of solar cells are being installed worldwide - on roofs, in deserts, in fields. It's the fastest growing energy technology in the world by far. The growth rate is 30 to 40 percent per year. And if you look at the dollar volume, you're looking at the entire system volume, you're looking at probably 200 to 300 billion dollars a year. So you have a 200 to 300 billion dollars a year industry growing at 30 to 40 percent a year. So this represents a tremendous opportunity for our graduates. So, these advances came around because of improvement in silicon technology, improvement in the technology of solar cells, and in developing other new materials. For example, a material called cadmium telluride. Nobody worked on cad-telluride in 1973. And now, it's again an industry that's producing over 10 gigawatts of solar panels per year. That's 10 nuclear power plant. And it's an American company, First Solar. They are the leaders in this technology and I'm happy to say that I have some connections with First Solar. And some of my ex-students and ex-employees, actually one of my ex-Master's student, went to First Solar back in 1997 or 1998. And I believe he is still there. And, so he has played a role in developing that technology. It's a very exciting technology. You can deposit a thin film of cad-telluride, a thin on flexible substrates or glass substrates. And with an all-automated processing, the solar cell comes out. You don't have take silicon wafers and cut them up. Every day, a new technology comes around. Some of them work out, some of them don't work out. But that's the beauty of research. You come up with a new idea. And if it looks feasible, then you pursue it because there may be significant advantages to pursuing that idea. For example one of the technologies that I'm working on is to increase the efficiency of standard crystalline silicon solar cells from the current 20 to 24 percent conversion efficiency of solar energy into electricity to something like 35 percent. That would be a 50 percent increase in performance at almost no additional cost. Now why would anybody not do that. That would bring the cost down further, and reduce the amount of area needed to produce a certain amount of power which is always good. So people keep coming up with new ideas. And some of us pursue some of those new ideas, and it makes for a very exciting world. As far as the leading solar cell companies in crystalline silicon, China has taken the lead. It used to be in America, then Germany, and the last five years that has been all China. Because of interesting reasons. Nothing to do with technology, everything to do with economics and politics, but be as it may. But the technology is coming back to the U.S. There are a lot of new American companies coming up. The leading companies are all Chinese though. So on a related question, what are some of the technical challenges in solar cell technologies today? The first challenge is to increase the efficiency. The performance today limited to, you know, a silicon is 23-24 percent at best. In production, it's between 15 and 20 percent efficiency- conversion efficiency of solar energy into electricity. And we know how to increase it to 35 to 40 percent. And that's one of the major challenges. By using new materials, in addition to silicon, so it would be a combination of silicon and a new material - which will get us to like 35 percent and we don't see any technical reasons why it would not happen. And this is where one of the challenges are. Okay that's great. So moving on. Today this industry is witnessing aggressive competition. The leading chip companies, for example, are making their own integrated System on Chip (SoC) devices, and moving away from general purpose ASIC and off-the-shelf electronics. The Apple M1 chip is a classic example. Is this trend here to stay? Yes. Because a lot of the applications in semiconductors have nothing to do with computers. They're not going into the super high, super-fast computers. A lot of the applications have to do with driving your car, automating your home, running many of the machinery. And for that, you don't need the fastest computer chips. And so, they're going to have lots of different kinds of computer chips being manufactured and different companies are doing it. For example for automotive electronics, you really don't need the blazing speed computers but you do need computers which are extremely reliable, and which are extremely tolerant of heat, cold, all kinds of dusty environment. And so people make specific chips designed for automobiles and they make specific chips designed for washing machines, and specific chips for dryers, and specific chips for stoves and so on. So, the field is broadening. And a lot of little companies are springing up which are addressing the different applications. And Toyota, for example, has a very big program to make computer chips for automobiles. They don't want to rely on Intel or AMD or Taiwan Semiconductors (TSMC) to make the chips. They would rather have a dedicated foundry where they can make the chips. That's one of the reasons why Toyota did not suffer as much as some of the other companies from the current shortage of semiconductors for automobiles. It suffered but not to the same extent. So the field is very broad and, you know, the whole idea of optoelectronic devices, what we call photonic devices, you have to setup photonic foundries and you have to set up companies that just make up to electronic devices, the photonic devices. So that's completely separate from silicon. And also a very rapidly growing field. So from what you're saying, the industry is driven by the applications - whether it is automotive vehicles or whether it is power grid systems or whether it is solar cells. Correct! Moving on to the next question. How can our students develop their skills to be competitive in the semiconductor industry? Specifically, what courses and lab training are offered to students who want to learn to design, fabricate and test their own chips? They need to take the basic Electrical Engineering and Physics courses. I would even recommend taking a Material Science course dealing with SEM and characterization of The courses we offer in the department, of course, is EE 230 which is basically a circuit course that people should take so they understand how the semiconductors are used in different circuits. And then, EE 332 which is the basic course dealing with the physics of semiconductor devices that Santosh Pandey and I teach. And that's a very important course because it introduces you to the fundamentals. Then you can follow that with a fabrication course EE 432, which allows the students to actually fabricate a working CMOS device. CMOS is the basic computer chip device. Well they will appreciate the amount of precision that goes into manufacturing of semiconductors and all the different technologies that are used to make silicon into a working CMOS device. They will also learn how to measure and characterize their CMOS device. Then of course, there are beginning graduate courses EE 535 which is more advanced semiconductor physics, EE 536 which is basically advanced device physics of MOSFETs and transistors. EE 538/438 are very important courses dealing with optoelectronics. So these are some of the basic courses that people should take. Once they take them, they have the ability to be able to design the devices and to be able to fabricate whatever device they need to fabricate. We have facilities for fabricating many of the devices. Obviously not all the devices. If there are a couple of steps that you need to get done somewhere else, we know where to go, we know which other university can help us do that processing. So that's very important. So, what is the role of learning latest simulation tools for our students? It's very important. To design a new device for a specific application, you got to be able to simulate its performance. And the simulation tools allow you to do that. We also have simulation tools which simulate the process flow in order to make a device, starting with silicon wafer. So, we need to have knowledge of the appropriate simulation tools. And we have many of the simulation tools, not all. And we are always trying to upgrade our simulation tools. So our goal is actually to see whether the results from simulation tools actually match with the fabricated devices. Correct. We will fabricate the device based on what the simulation tools tell us, and then try to match it. As far as the nature of jobs that are offered to your graduating students, I understand probably they are placed as a process engineer in a semiconductor company and eventually they move on to become device-level engineers and lead a whole team. Is that the usual process? Yes. You'll be placed both, in the process engineering and also in device design and device analysis group. Because the students will a lot of experience doing measurements and analysis of the devices, both the ones that they are fabricated and the ones that, you know, we may have purchased. And, so, they go into simulation, design, they go into device analysis, they go into device reliability. Reliability is critical. If you have a car and a computer is controlling your steering, you don't want the steering mechanism to fail or your brake to fail. So the reliability is extremely important and what people shoot for is not 99 percent reliability. They shoot for 99.9999 percent reliability. Six nines! So they go into processing, reliability studies, device analysis, device design and then move up to head teams and entire labs. So the field is wide open and salaries are simply fabulous. Last year I placed two of my Master's students - M.S. in electrical engineering at Texas Instruments in Bay Area, Silicon Valley. Each one of them at hundred ten thousand dollars starting salary. And the Ph.D.s are getting 135, 135-140 thousand dollars plus bonuses. So what kind of qualities are these hiring companies looking for from our students? Good knowledge of semiconductors. Of course, a high GPA. 3.0 is about the minimum. They are looking for innovation. They are looking to see if you can think on your feet. They will ask you questions. Now you have taken the course, you've studied the device, and they will quiz you a little bit. They want to see if you can think on your feet. So they're looking for innovation, your ability to think on your feet. They're looking for people who are hard workers. They're looking for people who have the right background. And they are looking to see if you are enthusiastic. They can pick it up. They can pick it up in five minutes if you are enthusiastic or you're just applying for a job because it's money. They will know it. In two or three minutes, they will know whether you are truly interested or you're just looking for the money. Yes. So where do you see the field of semiconductor industry three to five years. In all of the technologies that I mentioned, namely better light emitting devices, better LEDs. Certainly, a very important semiconductor technology is going to be LIDAR for autonomous cars. Then the autonomous vehicles are going to require a lot of sensors - a lot of sensors and sensor fusion. You have to be able to take the outputs from all of the sensors and feed them into computers and analyze them and rapidly, very rapidly within microseconds, come to a conclusion saying - Hey, what's in front of me is a human being, I better brake. I better brake immediately or switch lanes. I mean those kinds of decisions have to be made in microseconds. So new kinds of sensor devices, LIDARs, fast computers, much more efficient solar cells, and power devices - the high power devices because renewable energy is going to require microgrids. And microgrids are going to require microgrid controllers which, of course, can very reliably switch very large amounts of power instantaneously so that even if the main grid goes down, the microgrid keeps functioning and can be used to bring up microgrid powered by solar or wind can be used to bring up the main grid. And then devices for cybersecurity - it is all semiconductors. Right. Our next question is on financial aid for students. So does the department offer scholarships and fellowships for undergraduate and graduate students who want to work in Microelectronic Research Center or in the semiconductor area? The department has lots of student fellowship. I don't even know the total number but it's very large. There are special scholarships for women. There are certainly scholarships for underrepresented groups. And there are scholarships for students who show interest and have appropriate GPA. And they are all available. The best person to ask about all the vast scholarship and fellowship opportunities that we have is probably Vicky Thorland-Oster in the advising office. She knows all of them. I don't. But we do have some limited scholarships and fellowships available, certainly for graduate students. Some of us have chaired faculty positions and we use those to offer financial aid, certainly for graduate students. And for undergraduates, for some undergraduates, we also have fellowship and scholarships available. And Vicky would be the best person to tell you about that. So on a last note. Any final word of advice for our students who want to excel in semiconductors. Take an interest. Be proactive. Come and talk to the different faculty working in the group. And we are all looking always for bright and creative students who are enthusiastic. If you show enthusiasm and interest, we are interested in you. All we ask in return is that you work hard and put your heart into it because in life if you are passionate about something, you will achieve a lot. If you're not passionate you won't. I think we answered all the questions. Thank you so much for our discussion and all the valuable advice that you gave to our students. We hope to chat with you again in the future. Thank you so much. Thank you.