The microwave and low frequency noise characteristics of 6 inch InAlN/AlN/GaN high electron mobility transistor (HEMT) were demonstrated and investigated on silicon-on-insulator (SOI) substrate for the first time. The InAlN HEMT on SOI substrate was grown by metal organic chemical vapor deposition (MOCVD) on a p-type (111) Si SOI substrate with a p-type (100) Si handle wafer for possible heterogeneous integration. The Raman spectroscopy measurement indicates that the smaller epitaxy stress was obtained by adopting SOI wafer and X-ray diffraction measurements revealed that InAIN HEMT on SOI achieves a flat surface and an abrupt heterointerface. The InAlN HEMT on SOI exhibits a lower leakage current compared to the device on high resistivity (HR) Si substrate and thus improves the off-state breakdown voltage from 134 V to 198 V. Moreover, the buried SiO2 in SOI substrate also efficiently suppresses the signal loss resulting in the better bandwidth and the microwave power performance. Based on the low frequency noise measurement, InAlN HEMT on SOI substrate also performs a relatively slight degradation after hot carrier stress.

This study investigated the temperature dependence of the current-voltage (I-V) characteristics of Al-doped MgxZn1-xO/p-AlGaN junction diodes. The n-type Al-doped MgxZn1-xO (AMZO) films were deposited on p-AlGaN using a radio-frequency (rf) magnetron sputtering system followed by annealing at 700, 800, and 900°C in a nitrogen ambient for 60 s. The n-AMZO/p-AlGaN diode at a substrate temperature of 25°C showed the lowest leakage current in reverse bias. The n-AMZO/p-AlGaN diode with an AMZO annealed at 900°C demonstrated the lowest reverse leakage current. The temperature sensitivity coefficients of the I-V characterizations were obtained at different substrate temperatures (25, 50, 75 100, and 125°C), providing extracted values of 6.4, 7.6, and 5.6 mV/°C in forward bias and −20, 5.6, and 0.8 mV/°C in reverse bias for the AMZO films annealed at 700, 800, and 900°C, respectively. The n-AMZO/p-AlGaN junction diode fabricated with AMZO annealed at 900°C demonstrated the lowest temperature dependence. In addition, the light emission was derived from the forward-biased junction, and near-ultraviolet light emission was evident at all of the p-n diodes. Based on these findings, the n-AMZO/p-AlGaN diodes are suitable for GaN-based heterojunction bipolar transistors (HBTs) and near-ultraviolet light-emitting diodes (LEDs).

In this study, a high-performance InAlN/GaN high electron mobility transistor (HEMT) was fabricated using low-temperature microwave annealing (MWA) as the ohmic metal alloy process for the first time. Ni-Al alloy aggregation is significant for InAlN devices because of the high Al fraction in InAlN layer. Furthermore, the indium segregation and out-diffusion of the InAlN barrier layer resulted in lower drain current and the formation of extra trap centers. Compared with traditional rapid thermal annealing with a high-temperature process window, MWA results in simultaneously superior ohmic contact and wafer sheet resistances because of the superior surface morphology of the ohmic metal alloy in the MWA device. Moreover, the heterostructure interfacial quality of two-dimensional electron gas density can be maintained through low-temperature MWA, as indicated by reciprocal space map measurements. Furthermore, Baliga's figure-of-merit calculation indicated that the MWA-InAlN HEMT had superior DC characteristics, providing improved device radiofrequency bandwidth and output power density performance.

The low-frequency noise (LFN) and reverse recovery charge characteristics of a six-inch InAlN/ AlN/GaN Schottky barrier diode (SBD) on the Si-on-insulator (SOI) substrate were demonstrated and investigated for the first time. Raman spectroscopy indicated that using SOI wafers lowered epitaxial stress. According to the DC and LFN measurements at temperatures ranging from 300 to 450 K, the InAlN/GaN SBD on the SOI substrate showed improved forward and reverse currents and achieved a lower reverse recovery charge, compared with a conventional device.

High breakdown voltage and thermally stable AlGaN/GaN Schottky barrier diodes (SBDs) were fabricated using diamond-like carbon (DLC) anode design on a silicon (111) substrate. The DLC metal-hydrocarbon target in this study is tungsten-carbide and this film coating was prepared by reactive DC magnetron sputtering in a high temperature chamber. Based on the measured Raman spectrum, a broad peak with two shoulders at approximately 1365 cm−1 (D peak) and 1570 cm−1 (G peak) can be observed and the intensity of D peak versus G peak for DLC in this study is about 1.37 by considering both coefficient of thermal expansion and conductivity. The lower serial resistance was observed in Ni/DLC anode SBD and this characteristic was concluded that the junction heat during high current operation was dissipated through the surface DLC anode immediately and thus the thermal accumulation induced resistance was improved. Temperature dependent low frequency noise (LFN) and reverse recovery measurements both indicated that the Ni/DLC anode design exhibited a highly potential for being operated at high switching frequencies and high temperatures with low switching loss.