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Undergraduate Researchers

Nathan Smith

Nathan Smith, Physics/Mathematics

SURF Scholar

“Optimization and Modeling of Metal-Oxide-Semiconductor (MOS) Photoelectrochemical Cells”

Solar energy represents one of the most promising and potentially useful fields in terms of renewable energy and thus the importance of developing and improving solar cell designs and directives is extremely high. Photoelectrochemical cells are one of many innovations on the concept, and often utilize the classical method of gathering electricity from light via the photoelectric effect and then using that electricity to dissociate water to generate hydrogen for subsequent electricity generation by fuel cells. This research focuses on the use of metal-oxide-semiconductors (MOS) with metallic Pt collectors on an oxide-covered p-type Si bulk. In order to maximize the energy harvested from the sun many aspects of semiconductor physics must be analyzed and optimized in these solar cells. Various design considerations such as direction of illumination, the geometry of catalytic collectors, the nature of the tunneling oxide layer, and the incorporation of a multiple junction (tandem) structure. Using MATLAB and the Python-based FiPy engine, the influence of changing these various cell design parameters can be analyzed and then tested on solar cells created in the laboratory. The trends determined will hopefully allow the development of more advanced and efficient PV and PEC cells. Silicon is the primary element being evaluated in the is work due to it's low cost, large elemental abundance, and ability to efficiently harvest solar energy. A thin SiO2 layer serves as the tunneling oxide and the collectors are made by depositing platinum on the surface via electrodeposition (for smaller sizes) or a shadow mask technique (for larger sizes). The sun delivers a huge amount of energy to the Earth's surface every day (180 W/m²), most of which is absorbed and dissipated instead of being put to proper use; improving PV and PEC technologies can change this.

How did you find out that you could do research in your field in the summer?

The Meyerhoff program introduced me to the idea of research internships during undergraduate summers. Since freshman year they have encouraged many applications to many places, including the Summer Undergraduate Research Fellowship (SURF) program at the National Institute of Standards and Technology (NIST.) Before I came to college I had never noticed research opportunities or even heard of them or thought about them. As a Physics/Mathematics major, I had kind of thought all the internships available were more for the life sciences as those were the only ones I had ever heard about.

How did you know that research at NIST was what you wanted to do?

My father has worked at NIST for quite a while and on the few occasions I visited the campus I always loved it. Physics has a huge presence at NIST, which is a delightful change of pace from what I usually see. I liked the idea of starting my first research experience at somewhere close and comfortable that I also knew for sure would be a great place. I'll be back next year if I am fortunate enough to be accepted again.

Did you apply to other places?

I applied to several other places such as NASA, APL, and a few REUs at various universities across the country. I was rejected or did not hear back from all of them.

Was the application difficult to do? Did you have help with this?

The SURF program application is very straightforward, in my opinion. There are some finer details to work out with the college, but for UMBC at least, Ms. McGlynn makes everything you need to do extremely clear and is quite helpful throughout the entire process even going as far to review your personal statement and resume. By the time your application is sent off there is essentially zero chance that anything is incorrect.

What was your summer research project?

My project dealt with the modeling and optimization of metal-oxide-semiconductor electrochemical solar cells. The purpose of the photoelectrochemical cells is to take light and convert it into electricity and use that electricity to break water into hydrogen gas and oxygen gas, thus providing hydrogen gas for fuel cells. The project deals heavily in renewable energy and aims to make silicon-based solar technologies more viable. I was altering solar cell geometries and composition to attempt to improve the efficiency and ensure that the voltage generated is enough to split water.

Who was your mentor for this project?

My mentor is a post-doctorate student named Daniel Esposito. I could not have asked for a better mentor. I also worked with
Dr. Jon Guyer (who was invaluable as well) when it came to the more complicated FiPy partial differential equation solver.

How much time do you put into this work?

I worked five days a week from around 7:30 a.m. to 4:30 p.m. for 11 weeks over the summer, so quite a bit of time. The project was large and interesting; I could have used more time!

Were you paid? Where did you live?

SURF students are paid $5,500 for the 11 weeks of work, which is a very good deal. I commuted from home, but I know that NIST will house most of the SURF students at Hyatt House (a nearby hotel) in very accommodating conditions, so that is certainly an option.

What academic background did you have before you started?

I had no previous research experience, but am a rising junior Physics/Mathematics major with ~115 credits under my belt. I have a job setting up labs at the UMBC Physics Department and am fluent in Python as well as MATLAB and Mathematica. Academically I was rather strong, but in terms of research I was completely new to it.

How did you learn what you needed to know for this project?

My mentor gave me a few papers to read and there is a wonderful website called PVCDROM that provides a wealth of information on how solar cells function and the semiconductor physics behind them. Google also played a large role in my learning.

What was the hardest part about your research?

The hardest part would have to be learning to research. When I had problems in classes, I can check my answers and ask questions. Here, I can still ask questions, but what makes this research is that NIST doesn't know the answers; that's why the SURF students are working on these problems, to find answers. It is a bit unnerving at first when you come up with a result and you can't know whether or not it's correct because it's brand new.

How does this research relate to your course work at UMBC?

My research had multiple tie-ins to my Modern Physics course and I was glad to have had it before hand as I was better equipped to understanding the physics behind semiconductors. The classes on/using MATLAB, Mathematica, and Python were invaluable. Having programming knowledge beforehand was very useful and it seems that most of the friends I made here use programming in their research as well.

What is your advice to other students about getting involved in research?

Try it. I find it extremely rewarding and fun, but not everyone will. Best you don't go through undergrad never taking these opportunities and then get into a research position because it's what you THINK you want and find out instead that you hate it. Find out now. Also, don't get discouraged if you're not accepted the first time, try again. I applied to 17 places my freshman year and got into none of them.

What are your career goals?

I want to get my Ph.D. in physics and go into research at a fine establishment such as NIST. After a nice long time as a researcher I hope to return to academia as a physics professor at a research university.

7/18/2012