Abstract
In this thesis, we used TCAD for fitting AlGaN/GaN heterojunction Transmission Line Model (TLM) I-V characteristics. A physics-based model of self-heating is included in TCAD simulations to investigate the internal device behavior. A dual metal Schottky Barrier Diode (SBD) is also simulated with the constructed models. The fitting errors of less than ±10% for DC I-V characteristics in both cases have been achieved. Another topic of this thesis is to design a normally-off p-GaN MOS-HEMT. A p-GaN MOS-HEMT with Al2O3 as the gate dielectric can significantly reduce the gate leakage current and achieve normally-off operation. To build the best performing device we optimized the channel length and doping concentration of the p-GaN. A p-GaN MOS-HEMT performance can also be improved by adding an i-GaN layer as the channel layer. Compared with a p-GaN MOS-HEMT, the i-GaN layer design reduced the threshold voltage and increased the saturation current. The i-GaN channel MOS-HEMT with a channel length of 0.4µm and a gate-drain length of 10µm shows a specific on-resistance as low as 3.7mΩ•cm2. The channel region resistance is 0.41mΩ•cm2 which contributes about 11% of the total resistance. The largest part of the total resistance is 1.75mΩ•cm2 from the gate-drain distance and it contributes about 47%.