MIT Department: Electrical Engineering and Computer Science
I am a rising senior at Columbia University majoring in Electrical Engineering, with a focus in photonics and semiconductor devices. I am driven by the potential of engineering to improve people’s lives and level social inequalities. I aspire to earn a PhD in Electrical Engineering and apply my training to developing more affordable and accessible renewable energy technology in developing countries. In my free time, I lead an Engineer Without Borders project developing a solar-powered water distribution system for the communities of Izgouaren and Ilguiloda in Morocco. I also love to hike and explore my city.
2019 Research Abstract
Electrical Characterization of Non-stoichiometric Tungsten Oxide
Alice Wu1, Alon Vardi2 and Jesús del Alamo3
1Department of Electrical Engineering and Computer Science, Columbia University
2, 3Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology
Inside each smartphone today lies several hundred billion transistors, which are essentially tiny switches that serve to compute and store data. The foundation of this technology is silicon, a semiconducting material. As demand continues to grow for higher performance devices, new semiconductor materials present opportunities to investigate for desirable properties that may enable improved performance. Here, we examine non-stoichiometric tungsten oxide, WOx, which has garnered interest as a surface transfer dopant for diamond-based electronics. Using atomic layer deposition, we made six samples of WOx thin films with different deposition conditions: (1) using either O3 or H2O as the oxygen precursor and (2) using a deposition temperature of 300 oC, 330 oC, or 350 oC. Each sample was then split in half, with one half fabricated into resistors and the other half fabricated into transistors. The samples deposited at 300oC generated too little current to be measured properly. All of the samples demonstrated semiconductor characteristics. We find that WOx deposited using O3 as a precursor has a larger oxygen-to-tungsten ratio and a sheet resistance 4-5 levels of magnitude greater than WOx deposited using H2O as a precursor. The transistors exhibited very low transconductance, and the transistors could not be turned off, so thinner WOx films would be needed to achieve more ideal transistor behavior. The W oxidation state was found to be very sensitive to presence of H2O, which reduces W, so exposure to H2O should be prevented after deposition when using WOx in diamond-based or other electronics.