High-temperature ultraviolet detection based on surface photovoltage effect in SiN passivated n-GaN films

We investigated the surface photovoltage (SPV) effect in n-GaN layers passivated with various insulators, i.e., Al2O3, SiO2, and SiN for ultraviolet (UV) light detection. We revealed that SPV in SiN/GaN shows markedly different behaviour than in oxide/GaN, i.e., the photo-signal exhibited very fast response (1 s) and recovery (2 s) times, contrary to oxide/GaN, and it was thermally stable up to 523 K. Furthermore, SPV spectra for SiN/GaN showed a sharp cut-off edge directly corresponding to the GaN band gap. We explained these results in terms of the different band structure of SiN/GaN and oxide/GaN junctions. All the observed properties of SPV response from SiN/GaN indicate that this relatively simple system can be applied to sensitive high temperature visible-blind UV detection. Published by AIP Publishing.