GaN MSM photodetectors with TiW transparent electrodes

TiW films were deposited onto glass substrates and GaN epitaxial layers by RF magnetron sputtering. It was found that TiW film deposited with a 300 W RF power could provide us a high transmittance and a low resistivity. GaN-based ultraviolet metal-semiconductor-metal (MSM) photodetectors were also fabricated. It was found that photocurrent to dark current contrast ratios were 4.35, 4.6 x 102 and 5.7 x 104 for the photodetectors with ITO, TiN, and TiW electrodes, respectively. The large photocurrent to dark current contrast ratio could be attributed mainly to the fact that TiW can form a high Schottky barrier height on the surface of u-GaN epitaxial layers