Beaming with Electrons

by Meredith Meyer

Research used to intimidate me. I’m still in high school, and I didn’t think that I could run experiments like the revolutionary ones I had read about. However, this summer, I ignored the daunting feelings that I linked with research, and I worked with graduate student James Perkins at The Ohio State University (OSU) in the Center for Emergent Materials (CEM) in Professor Brillson’s physics laboratory.

Before my research work began, I had no idea what to expect. I came across the opportunity through my high school, so I asked the student that worked in Professor Brillson’s lab last year, Jasneet Singh, who was the previous high-school board member on this blog and a year ahead of me in school, how she felt about her experience. She told me how fun and easy-going everyone was, but I still had trouble believing her, which I later found out was ridiculous of me.

I was extremely nervous my first day; all I knew was that I would be in a physics lab, and I was pretty sure we wouldn’t be dealing with mechanics—the only course I had ever taken in the subject. However, after weeks of freaking myself out, I walked into the Physics Research Building at OSU and met a few members of Prof. Brillson’s group. Unlike what I had feared, all the students were kind and understanding when I explained that I was clueless about their research. So, for my first few days, a couple of different graduate students taught me about the work they did. In the morning I read scholarly articles, and in the afternoon I clarified what I had read with the graduate students. (Coincidentally, now around six months after my research experience, my AP Chemistry class just began covering a few of the ideas I had to learn for my summer research project.)

I first learned about semiconductors, which have both conducting and insulating properties. I discovered that semiconductors have a band gap, which is the energy difference between the electrons held by the atom (valence band) and the electrons free to move within the material (conduction band).

I worked with zinc oxide (ZnO), which is a semiconductor used in computer equipment and detectors. The graduate student I worked with, James, had samples of ZnO doped with varying levels of magnesium (Mg) to create a new semiconductor with different conductive properties called magnesium zinc oxide (MgZnO). (Doping is a process in which you add another substance to a semiconductor to change its electrical properties.) Zinc oxide has a smaller band gap than magnesium zinc oxide (MgO), so when they were combined into MgZnO, one could theoretically control the band gap depending on the level of magnesium doping. Our purpose was to see how the levels of Mg affected the band gap in order to understand a way for future band gap control and widen its uses.

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The samples of MgZnO that I tested.

For the six weeks that I spent at OSU, a day in my life started with taking data. After a week of learning and training, I was responsible for running the experimentation on the MgZnO samples. Through a process known as depth-resolved catholdoluminescence spectroscopy (DRCLS), I could characterize the electrical properties of the samples of MgZnO with varying levels of Mg content. (DRCLS is a method in which an electron beam is shot at a sample to excite the sample’s electrons at varying depths into the sample, which depend on the beam energy because at higher beam energies, one tested deeper into the sample. The excited electrons would then emit energy in the form of light, and we looked at this light energy to characterize the sample.)

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The equipment I used to run DRCLS. On the left is what the equipment I used looked like with the lights on, and on the right is what it looked like with the lights off, which is how I ran the experiment.

Every morning I spent my days in a dark lab (since we were looking at the light released, we couldn’t have any outside light interfering), and I took data on at least two spots on each sample at 25 different beam energies. The equipment I got to use to run DRCLS looked like it was straight out of Star Trek: The Original Series, and when I messed with the dials to change beam energies, I felt like I was the star of a science fiction movie.

After I collected data in the morning, I returning to the office and looked through the data for James. I found the spots of the data that represented major defects or the band gap energies. Then I shared my findings with James and eventually Professor Brillson, who was thrilled to see that we found that as we increased the level of Mg, the band gap widened, but the number of electrical defects decreased and then increased once we had more than 50% Mg.

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An example graph of the data I took on a sample of MgZnO with DRCLS.

At the end of my research project, I presented these findings to a group of graduate students, OSU professors, and  students and teachers from my high school, and my mentors are submitting my research to the scientific journal Applied Physics Letters in a paper that will list me as co-author.

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A group picture of the OSU professors and the students from my high school that participated in summer research. That’s me with the long black hair! Source: Columbus School for Girls

At first, I was extremely apprehensive about research. I thought I would mess something up and ruin the entire study, or I wouldn’t be smart enough to actively participate. However, I discovered that my fears were irrational. Everyone I met was encouraging and understanding: they were patient as I struggled for a few days to understand band gaps and DRCLS, and even though I began my research with knowing only a simple definition of what a semiconductor was, I ended up feeling confident in the background information of all my work. I think I learned more about physics in the six weeks I spent at OSU than the full year class I took at my high school. After this summer, I know that I want to participate in some kind of research during my undergraduate years, for example, biological research related to neuroscience to coordinate with my passion for medicine. My experience with physics taught me that I love to experiment, and, more importantly, I am no longer intimidated by research one bit.

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About Meredith Meyer

BioPictureI am a senior at Columbus School for Girls (CSG). I was born and raised in Columbus, Ohio, but I am excited to leave my hometown for college next year! I love to read, watch TV (too much according to my parents), play field hockey, and work on my school’s FIRST Robotics Team, which I am a captain of this year. I’ve always wanted to become a doctor, but I am keeping my options open for my future college major—maybe I will choose physics!