(285h) Modeling and Simulation of Hydrogen Diffusion and Impurity Passivation In n- and p-Doped III-V Semiconductor Photonic Materials
Hydrogen has been identified as an effective passivating species for n- and p-type III-V semiconductor photonic materials. Briefly, upon exposure to hydrogen plasma, hydrogen atoms penetrate the surface of a semiconductor substrate and diffuse through the various thin-film layers. These atoms then react with n- and/or p-type impurities to form a passivated complex, thereby causing electrical or photonic isolation of these regions. As this technique is presently used in photonic device fabrication, it is desired to have a robust, predictive reaction-diffusion model to more efficiently develop passivation techniques with respect to time and cost. The purpose of this work is to develop a fundamental model of the relevant kinetic and transport mechanisms involved in the passivation of photonic materials (with particular emphasis on Zn-doped, p-type InP), to create a predictive computer simulation, and to validate it against experimental data. To meet these objectives, a theoretical model was developed that incorporates concentration-based and potential field-enhanced diffusion of hydrogen in n- and p-type materials while also considering the passivation reactions between the diffusing hydrogen and photonically active impurities. Experiments have been performed to follow the diffusion and/or reaction of deuterium (as a model for hydrogen) in undoped and Zn-doped InP substrates and heterostructures, with deuterium and impurity concentrations determined using SIMS and with the optoelectonic activity of Zn determined using Polaron measurements. This data has been used to determine key parameter values included in the model as a function of temperature, which are subsequently used to predict diffusion-passivation profiles in other thin-film substrate configurations. Computational results have shown excellent agreement between experiment and theory, predicting the passivation profiles and penetration depths for various heterostructures. Present work is focused on expanding the simulation to another computational platform, with development of n-type, p-type, and merged n/p-type versions to address different impurities and their positions in the crystal structure of the substrate. Future work will seek to validate these simulations and to more fully explore the behavior of this reaction-diffusion system under a wider array of thin-film structures.