Abstract
The material characteristics of Gallium Nitride used in the power device applications are superior than silicon owing to the wide bandgap (~3.4 eV), high critical electric field (3.4 MV/cm), high electron saturation velocity (2*107 cm/s), and high thermal conductivity (2.3 W/cm．K). Recently, many publications related to the AlGaN/GaN-on-Silicon Schottky Barrier Diodes (SBDs) have been discussed. One of the most critical issues is lowering the turn-on voltage owing to the wide bandgap nature of the material, which can increase the conduction loss and seriously degrade the efficiency of circuits and systems. This thesis presents the simulation and measurement results. In the simulation, the Silvaco TCAD software is used to simulate the turn-on voltage and e-field distribution for that with/without anode recess. Also, by considering two different contacts (Schottky and ohmic) with different silicon substrate doping and with/without AlN layer (between GaN and Silicon), the vertical distribution of e-field and carrier concentration is simulated to discuss the breakdown location and the e-field distribution. In the measurement, the anode recess technology is employed to reduce the turn-on voltage, which forms a Γ-shaped electrode and acts similar to a field plate to alleviate the high electric field. The SBDs with anode-recessed structure is presented to simultaneously improve the turn-on voltage from 1.1 V to 0.7 V and the breakdown voltage (VBK) from 1600 to 2200 V. The turn-on voltage reduction can be attributed to the increased tunneling probability by directly contacting the 2DEG with Schottky metal. Also, the high VBK can be attributed to the smooth contact interface and the 2-μm Schottky extension to alleviate the peak e-field intensity.