The development of high-power, High Electron Mobility Transistors (HEMTs) has seen a major leap forward during recent years. Accurate simulation models are needed to fully explore the potential of the devices. We employ a Monte Carlo technique to investigate stationary electron transport in GaN and InN. The simulation results are used as a basis for the development of analytical models for these two materials and their alloys, suitable for the simulation of GaN and InN-based electron devices. We analyze different structures such as traditional AlGaN/GaN HEMTS, double heterojunction devices, and also novel InAlN/GaN transistors. The latter provide higher polarization charges without the drawback of high strain. A performance superior to that of AlGaN/GaN structures is therefore predicted. However, the Schottky-gate devices share gate current leakage issues, which can been addressed by adding a dielectric layer between the gate and barrier layer. This is the reason why we also focus on MOSHEMTs, and the influence of the insulation layer on device performance. Our work also includes the optimization of various applications (high-power, high-frequency or high-breakdown), involving various enhancement techniques. We assess the impact of different effects, such as thermionic field emission and self-heating on device performance. Since the longitudinal electric fields in the channel exhibit rather large values, we employ a hydrodynamic transport model.
Due to the brisk interest in normally-off devices, several approaches are currently being analyzed, one being the addition of an InGaN cap layers, which raises the conduction band of the AlGaN/GaN interface. Furthermore, we study the AC characteristics of the devices. Exploring different mobility models, we achieve good predictive results for RF transconductance, capacitances and cut-off frequency for devices with various geometry setups. A secondary field of research comprises novel solar cells on n-type silicon, featuring a metal-insulator-semiconductor layer structure and optimization for greater efficiency.