Winston Peloso, COL’23, Princeton, NJ
This summer I sought to model charge transport in new materials using photoconductivity experiments. I fabricated measurement devices in the cleanroom, connected the devices to a multi-machine measurement setup, and used a lock-in amplifier to gather data. I also made a test device to ensure the setup worked as expected. There were several hiccups due to the experimental signal being weaker than expected – substantial modifications to the device were required before any signal was visible at all. But after figuring out and implementing these modifications I was able to study charge carrier transport in various ways, and will continue this study during the school year to complete a thesis in fulfillment of the requirements of the physics master’s program.
Photoconductivity spectra in wide bandgap semiconductors provides useful information about their electronic structures: if illuminating a sample with a particular wavelength of light increases its conductivity, then there must be an electronic transition at the associated energy that frees charge carriers. If this energy is less than the band gap, we can often attribute the transition to defect levels. Materials with such defects are under investigation for use in solar cells, high-performance transistors, spin-light interfaces, quantum sensors, and other next-generation technologies. Photoconductivity is a broad, practical characterization tool that can test these applications and aid their engineering.
Though I’ve worked in research before, this experience gave me the opportunity to undertake a particularly interdisciplinary experiment. Penn is uniquely suited to interdisciplinary science due to its collaborative culture, which I participated in by carrying out the project using resources in four different labs. My graduate student advisors helped me access these networks, which I will carry forward with me. I also gained experience with fabrication and measurement techniques that I will likely use in future studies, making me a more competitive applicant to graduate school. This experience affirmed my commitment to a research career and gave me a taste for its richness when working at the cutting edge.
This is part of a series of posts by recipients of the 2022 Career Services Summer Funding Grant. We’ve asked funding recipients to reflect on their summer experiences and talk about the industries in which they spent their summer. You can read the entire series here.
