18. Physical-Based Simulation of a GaN High Electron Mobility Transistor Devices

Silicon-based semiconductor devices are rapidly approaching the theoretical limit of operation, making them unsuitable for future military and industrial applications. In a high electron mobility transistor (HEMT), two-dimensional electron gas (2DEG) which is formed at AlGaN/GaN interface is a critical part to tune the performance of HEMT devices. Inserting high bandgap layers, especially AlN spacer layer between AlGaN and GaN layer improves 2DEG density, mobility, and effects on quantum well. ATLAS toolbox of Silvaco results shows ID-VDS characteristics of the 1 μm gate length. Simulation results show both piezoelectric and spontaneous polarization effects at the interfaces of Al0.30Ga0.70N/AlN/GaN structure, contrary to the conventional HEMTs. The insertion of the very thin AlN interfacial layer (1 nm) supports high mobility at high sheet charge densities by increasing the effectiveness and decreasing alloy scattering. Devices based on this structure exhibit good DC and RF performance.