Electrical properties of Ni/n-GaN Schottky diodes on freestanding m-plane GaN substrates

The electrical properties of m-plane Ni/n-GaN Schottky diodes grown via metalorganic chemical vapor deposition were investigated. Under growth at 1,120 degrees C with a V/III ratio of 1,000 (growth rate of 100 nm/min), the residual Si, O, and C impurity concentrations in the m-plane GaN layer were below the secondary-ion mass spectroscopy detection limit. The surface of the Si-doped n-GaN epitaxial layer on the 5 degrees-off m-plane GaN substrate consisted of steps and terraces. A linear correlation between the carrier concentration and the Si atomic concentration was clearly observed from 1 x 10(17) to 5 x 10(15) cm(-3). The reverse current-voltage curves were fitted using the thermionic field-emission model at the measured carrier concentration and q phi(B). The leakage current of the diodes under a reverse bias was effectively suppressed at a low carrier concentration of 4.6 x 10(15) cm(-3). (c) 2017 The Japan Society of Applied Physics