Characterization of peripheries of n-GaN Schottky contacts using scanning internal photoemission microscopy

Abstract We applied scanning internal photoemission microscopy (SIPM) to clarify the electrical characteristics on the electrode periphery of Ni/n-GaN Schottky contacts. Two types of Schottky contacts with different electrode formation methods were prepared. For the samples in which the Ni contacts were evaporated through a metal shadow mask, in the scanning electron microscopes (SEM) observation, the electrode edges were tailed and the tail was divided into two contrasts, a bright region with a width of 15.5 μ m from the electrode edge followed by a dark region with a width of 32 μ m. The SIPM signal was obtained from the first 16 μ m tailing region, and corresponded with the SEM images. For the photolithography sample, a sharp edge less than 1 μ m wide was obtained and no increase in SIPM signal was detected on the edge. These results indicate SIPM is able to characterize the electrical properties of electrode periphery in conjunction with the structural characteristics.