Abstract
Research in high power and high frequency devices on Gallium-Nitride- based High Electron Mobility Transistor(HEMT) has become more and more popular due to their outstanding material characteristics which including wide bandgap, high critical electric field, high electron saturation velocity, and high thermal conductivity. Among them, owing to the high density of two-dimension electron gas only depending on the spontaneous polarization without strain introduced by lattice match, the InAlN/GaN Heterojunction Field Effect Transistor using InAlN as barrier layer is suitable for high frequency applications. However, the high leakage current and low breakdown of InAlN/GaN device is still an issue for achieving high power performance. In this thesis, MIS-HEMT using Al2O3 as the insulator layer with different gate recess depths was investigated to increase the breakdown voltage while maintaining good high frequency performance. The defects and traps generated at the Metal-Insulator interface and Insulator-Semiconductor interface and the non- optimized gate recess depth could be responsible to the relatively poor DC performance of the transistors. However, the result still shows that using Al2O3 as insulator layer can improve the breakdown voltage up to 62.5%. In addition, device achieves frequency performance with f_max=4.38GHz and f_T = 1.95GHz. With optimizing the depth of gate recess and annealing device after the deposition of Al2O3 insulator layer, the improvement of performance can be expected.