Hydrogen passivation is an important step in the fabrication of optoelectronic devices. Passivation isolates components on a semiconductor substrate by electronically and/or photonically deactivating doped regions. Hydrogen has been identified as a passivating species for n- and p- type III-V semiconductor materials. The substrate is exposed to hydrogen plasma, which diffuses through the doped film. The hydrogen reacts with dopant atoms to form neutral complexes, thereby passivating the region. The purpose of this work is to create a predictive computer simulation using a physically-based theoretical model and to validate the simulation against experimental data. The model involves both the reaction and diffusion of passivating species with dopant atoms, subject to charge-induced field effects. Computational work has focused on creating a stable numerical simulation using MATLAB, which individually tracks all species concentrations and electrical potential as a function of time, position and system parameters. This yields physical insight into the passivation process. The theoretical model has been implemented for p-type material using a finite difference scheme, employing an iterative method for solving the time-evolution of the species in the passivated region. Simulation results show excellent agreement with experiments using Zn-doped material. Work continues to focus on increasing the robustness of the simulation to handle more physically-complex scenarios, including annealing, heterostructures, and both n-type and mixed n/p-type substrates.
Isaac Lavine is a junior Chemical and Biomolecular Engineering and Mathematics major at Lafayette College. On campus he is involved with the Ultimate Frisbee team, Tau Beta Pi, tutoring in Calculus Cavalry, and recently joined Salsa Club! He also enjoys reading about economics, politics and current events. In previous years he has worked as a chemistry laboratory assistant at the University of Massachusetts, and as an REU student at Harvard Forest before beginning research with Professor Levinson last summer. Significant challenges have been overcome since beginning the project and it is his hope that the scope of the project may be expanded before graduating.