Effect of Surface Morphology on Diode Performance in Vertical GaN Schottky Diodes

The properties of thick GaN layers grown by metal organic chemical vapor deposition on 2 '' HVPE substrates were investigated. Although the epilayer is smooth on a microscopic scale with high quality layers as evidenced by X-ray diffraction and photoluminescence, macroscopic morphological variations are observed on the wafer surface. These variations correspond to disparities in leakage current in fabricated Schottky barrier diodes, with rougher macroscopic morphology resulting in increased leakage current.