EFFECT OF SERIES RESISTANCE AND INTERFACE STATE DENSITY ON ELECTRICAL CHARACTERISTICS OF Au/SiO 2/n-GaN SCHOTTKY DIODES

We have investigated the current-voltage (I V) characteristics of (Au/SiO2/n-GaN) metal-insulator-semiconductor (MIS) Schottky diodes and compared with (Au/n-GaN) metal-semiconductor (MS) Schottky diode. The effect of SiO2 on the surface preparation of n-GaN (MIS) Schottky diode is analyzed. The extracted Schottky barrier height and ideality factor of the MS Schottky diode is found to be 0.79 eV and 1.45 respectively. It is observed that the Schottky barrier height increases to 0.86 eV and ideality factor decreases to 1.3 for MIS diode. The interface state density as determined by Terman’s method is found to be 3.79 × 1012 and 3.41 × 1010 cm 2 eV 1 for the MS and MIS Schottky diodes, respectively. In addition, the values of series resistance (Rs) are determined using Cheung’s method. The I V characteristics confirmed that the distribution of Nss, Rs and interfacial layer are important parameters that influence the electrical characteristics of MIS Schottky diodes.