Detailed Investigation of GaN Metal-Insulator-Semiconductor Structures by Capacitance-Voltage and Deep Level Transient Spectroscopy Methods

Detailed investigation of electrical characteristics of GaN metal-insulator-semiconductor capacitors (MISC) with a SiN insulating layer deposited by electron cyclotron resonance (ECR) plasma-assisted sputtering method has been performed focusing on a trap behavior by utilizing capacitance-voltage (CV) method and deep level transient spectroscopy (DLTS). From the CV measurements, hysteresis and ledge were clearly observed in the high frequency region, and they had dispersions of both frequency and sweep rate of gate bias. Traps and a slow minority carrier recombination rate in depletion layer are responsible to them. The observation of CV curves of the samples with different SiN thicknesses suggests that the traps which build ledge mainly exist in SiN bulk rather than SiN/GaN interface.