The effects of high-energy uranium ion irradiation on Au/n-GaN Schottky diodes

The I-V and C-V characteristics of Au/n-GaN Schottky diodes irradiated with 290-MeV U-238(32+) ions are presented. The U ions can penetrate the n-type GaN epi-layer with a thickness about 3 mu m grown on the c-plane of a sapphire substrate using the MOCVD technique, leaving a purely electronic energy deposition. The Au/n-GaN Schottky diodes were irradiated to successively increasing fluences from 1 x 10(9) to 5 x 10(11) ions cm(-2). The measured I-V curves show that the height of the Schottky barrier decreases after irradiation and that the Schottky barrier almost disappears when the ion fluence reaches 5 x 10(9) ions cm(-2). Meanwhile, the irradiation increases the series resistance. The C-V curves show that the capacitance drops sharply when the ion fluence reaches 5 x 10(10) ions cm(-2). The dielectric constant also decreases following the irradiation. The changes of the electrical properties are ascribed to the neutralization of the donor-like surface state and the acceptor-like surface state due to the migration of Au atoms at the interface of Au/n-GaN under energetic U ions irradiations. (C) 2014 Elsevier B.V. All rights reserved.