Device Performance and Reliability Improvements of AlGaN/GaN/Si MOSFET Using Defect-Free Gate Recess and Laser Annealing.

摘要

AlGaN/GaN high electron mobility transistors are promising for high frequency and high power application due to their unique properties. High-k dielectrics, such as Al2O3 and HfO2, are attractive materials which suppresses the gate leakage current of AlGaN/GaN high electron mobility transistors. Since the interface quality of AlGaN and high k dielectrics are critical to device performance, such as the threshold voltage and interface state density 201Dit202, it is therefore necessary to understand that the relationship between interface chemistry and device performance is fundamental for examining optimization strategies for device applications. Firstly, the impact of various chemical pretreatments on AlGaN surface is studied. Then the interfaces formed upon atomic layer deposition 201ALD202 of Al2O3 and HfO2 are investigated using in situ X-ray photoelectron spectroscopy 201XPS202. The impacts of ALD of Al2O3 and HfO2 on native AlGaN are studied by capacitance voltage characterization. The XPS and device results uncover a high density of interface states. In situ N2 forming gas and O2 plasma pretreatments prior to ALD as optimization strategies are investigated using in situ XPS, LEED and C-V characterizations.