Fabrication and characterization of compound semiconductor devices and their electrical and thermal simulation

Scandium Oxide (Sc2O3) and Magnesium Oxide (MgO) were demonstrated as promising gate dielectrics for GaN-based Metal Oxide Semiconductor High Electron Mobility Transistors (MOSHEMTs) and Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) along with being very good passivation layers for GaN/AlGaN HEMTs. I-V and C-V, G-V measurements were used to characterize the interface between oxide and GaN. Interface state density and breakdown field were extracted from these measurements (experimental data). These results of MOS diodes led to the first demonstration of GaN/AlGaN MOSHEMT using Sc2O3 as gate dielectric. The MOSHEMTs showed ∼40% more saturation drain-source current than that of HEMTs and gate of MOSHEMTs can be biased to +6 V as compared to max +2 V for HEMT. Use of Sc2O3 and MgO as surface passivation layer enhanced RF and microwave performance of these devices.; Temperature simulations on bulk GaN power diodes were performed using Finite Element analysis to compare the junction temperature of power diodes packaged with conventional wire bonding and flip-chip bonding technology. Superior heat dissipation was obtained for the flip chip bonded device. Finite difference thermal analysis of 850 nm VCSELs was carried out by writing a code in MATLAB. Thermal characteristics of 1550 nm VCSEL were also studied by using finite element analysis software called FlexPDE.; W-based Schottky contacts on GaN are attractive for applications requiring long-term thermal stability, such as combustion gas monitoring. The effect of deposition conditions on the electrical properties of W/Pt/Au Schottky contacts on n-GaN was studied.