| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 92 === We have studied the electrical properties of n-GaN (Ni/GaN) Schottky diode covered with variety of densities of V-defects. The I-V characteristics of the diodes with 100μm diameter indicated that as the densities of V-defects on GaN films increased from 4.1×105cm-2 to 1.03×107cm-2, the Schottky barrier height decreased from 1.44eV to 1.19eV and the reverse bias leakage current at -1V is increased sharply from 10-10A to 10-7A . Further studies on a single V-defect using conductive atomic force microscope (C-AFM) demonstrated that the value of forward current biased at 8V at V-defect side-walls appears to be one order higher than that of plain region, indicating that the conductivity mainly occurred at the side-walls of V-defect. Moreover, rather interesting I-V behavior was observed at reverse bias. Large reverse leakage current was observed on both the perimeter and crest-line of hexagonal V-defects, relatively few current leakage is observed on the facet of side-walls. Such I-V characteristics can be attributed to the appearance of large density of surface states in V-defects, which reduced the Schottky barrier height and provided alternating current leakage path at reverse bias. We believe that the appearance of large density of V-defect in GaN film is the major factor responsible for the current transports in a large-area Schottky diodes made from n-type GaN film.
|
|---|
