Electrical transport properties of Au/SiO2/n-GaN MIS structure in a wide temperature range

The temperature-dependent electrical properties of Au/SiO2/n-GaN metal-insulator-semiconductor (MIS) structure have been investigated in the temperature range of 120–390 K. Anomalous strong temperature dependencies of the barrier height (Φbo), ideality factor (n), interface state density (NSS) and series resistance (RS) are obtained. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (GD BHs) at the interface. It is evident that the diode parameters such as zero-bias barrier height increases and the ideality factor decreases with increasing temperature. The values of series resistance that are obtained from Cheung’s method is decreasing with increasing in temperature. The temperature-dependent current–voltage characteristics of the MIS diode have been shown a double Gaussian distribution giving mean barrier heights of 0.38 eV and 1.06 eV and standard deviations of 0.0561 and 0.2742 V, respectively. A modified ln (Io/T2) − q2σo2/2k2T2 versus 103/T plot for the two temperature regions gives φ b o ¯ and A∗ as 0.55 eV and 11.56 A cm−2 K−2, and 1.02 eV and 23.48 A cm−2 K−2 respectively. The Interface state density values are calculated by I–V and C–V measurements at different temperatures using Terman’s method. It is observed that the interface state density decreases with increase in temperature (120–390 K). Therefore, it has been concluded that the temperature dependence of the forward I–V characteristics of the Au/SiO2/n-GaN Schottky diodes can be explained with a double GD of the BHs.