Student: Ben Garland
Project: Exploiting Fixed Charge to Control Schottky Barrier Height in Si|AlOx|MoOx – based Tunnel Diodes
View: Research Poster (PDF) | Presentation (YouTube)
Department: Materials Science and Engineering
Advisor: Nicholas Strandwitz
Abstract
Solar cells provide clean, renewable energy without harmful emissions; however further development of solar technology is necessary to encourage its widespread adoption. Carrier selective contacts have become one of the leading advancements in photovoltaics with the most efficient structures exceeding 26% conversion efficiency. Selective carrier conduction implies that one type of charge carrier is preferentially collected at a materials interface. Carrier selectivity increases the efficiency of solar cells by reducing recombination at metal contacts and avoiding highly doped emitter layers. Popular selective contact materials are often transition metal oxides (TMOs) due to high optical transparencies and large work functions that cause electronic band bending in silicon. In contrast to previous reports, our recent studies have indicated that the interface of p-type silicon and sub-stoichiometric, amorphous molybdenum oxide (MoOx) allows a significant Schottky barrier to majority carrier holes that decreases the efficiency of hole-selective contacts. To alleviate this issue, annealed atomic layer deposited (ALD) alumina (AlOx) might be added between p-type Si and MoOx to introduce a negative interface fixed charge (Nf), decreasing band bending that would increase the Schottky barrier. Annealing the AlOx also allows interface trap passivation from diffusion of precursor hydrogen. In this work, we hypothesized that insertion of a tunneling ALD AlOx layer between MoOx and p-type Si will enable Schottky barrier height (ϕbh) minimization that is tunable with Nf, enabling a high efficiency hole-selective contact.
About Ben Garland
Ben M. Garland is originally from Oley, PA, USA. He worked as a research & development intern for Covanta Holding Corporation in Morristown, NJ, USA in 2017. He was an undergraduate research fellow from 2017 to 2018 and a research intern from 2018 to 2019 at Pennsylvania State University, State College, PA, USA. He received the B.S. degree in materials science and engineering from Pennsylvania State University in 2019. He is currently working toward the Ph.D. degree in materials science and engineering at Lehigh University, Bethlehem, PA, USA. His research interests include photovoltaics, thin film technology, and multifunctional materials and structures for energy applications. Mr. Garland is a member of the National Society of Leadership and Success.