Electrical characterization of MS and MIS structures on AlGaN/AlN/GaN heterostructures

Abstract

The forward and reverse bias I– V, C– V, and G/ ω– V characteristics of (Ni/Au) Schottky barrier diodes (SBDs) on the Al 0.22Ga 0.78N/AlN/GaN high-electron-mobility-transistor (HEMTs) without and with SiN x insulator layer were measured at room temperature in order to investigate the effects of the insulator layer (SiN x ) on the main electrical parameters such as the ideality factor ( n), zero-bias barrier height ( Ф B0), series resistance ( R s ), interface-state density ( N ss ). The energy density distribution profiles of the N ss were obtained from the forward bias I– V characteristics by taking into account the voltage dependence of the effective barrier height ( Ф e ) and ideality factor ( n V ) of devices. In addition, the N ss as a function of E c – E ss was determined from the low-high frequency capacitance methods. It was found that the values of N ss and R s in SBD HEMTs decreases with increasing insulator layer thickness.