Graded injector, wide bandgap light emitters and XPS studies of the InAs/GaSb heterointerface

Citation

Wang, Michael Wei-Ching (1995) Graded injector, wide bandgap light emitters and XPS studies of the InAs/GaSb heterointerface. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/653J-FX31. https://resolver.caltech.edu/CaltechETD:etd-10262007-091414

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. This thesis consists of two parts: research performed towards the development of a II-VI graded electron injector wide bandgap light emitter and characterization of the InAs/GaSb heterointerface, for application to InAs/[...] infrared superlattice detectors. Background and motivation for both projects are presented. Investigations of the II-VI graded electron injector light emitter consist of simulations to test the feasibility of a number of LED designs, band alignment measurements, materials characterization and device performance studies. The simulations, based on the Drift-Diffusion model with modifications to account for heterojunctions, demonstrate that the graded electron injector LED design is feasible. Improvements to the basic design can be implemented by incorporating confining layers and active layers with wider bandgaps using ternaries and quaternaries. The XPS measurements of the MgSe/[...] and MgTe/[...] valence band offsets show a deviation from the common anion rule with the valence band edge of the Mg-based semiconductor lower in both cases. The significance of these results is discussed. XRD, TEM and SIMS characterization of the graded injector devices reveal potential problems in material quality. Device performance characterization show good current-voltage and electroluminescence properties, but poor external quantum efficiency and device lifetimes. Characterization of the InAs/GaSb heterointerface consists of surface exchange reaction studies, band alignment measurements and interface abruptness studies. The XPS/RHEED investigation of surface exchange reactions shows monolayer exchange and Sb island formation for the Sb soaks of InAs surfaces, and As exchange with Sb past the terminating monolayer of Sb into the underlying GaSb for the As soaks of GaSb surfaces. The XPS band alignment studies show that the InAs/GaSb valence band offset is independent of interface composition, but changes with growth direction. Possible mechanisms for this behavior are discussed. Finally, the XPS, RHEED, cross-sectional STM and SIMS studies of the abruptness of the InAs/GaSb interface show that the GaSb-on-InAs growth direction is more abrupt than the InAs-on-GaSb growth direction. Mechanisms for this asymmetry in the interface abruptness are presented.

Thesis Files