The characteristics of different transparent electrodes on GaN photodetectors

The sputter ITO, TiN and E-gun ITO films deposited onto GaN as the transparent electrodes in the application of metal–semiconductor–metal (MSM) photodetectors were first fabricated and reported. The transmittance of sputter ITO, TiN and E-gun ITO films for thickness of 1000 Å was 94, 62 and 85%, respectively, at a wavelength of 400 nm. Unlike TiN films, the variation of transmittance of sputter ITO films was not sensitive to the thickness. Also, the effective barrier height of sputter ITO, TiN and E-gun ITO films to GaN was 0.46, 0.59 and 0.95 eV, respectively. Furthermore, the photo/dark contrast of sputter ITO, TiN and E-gun ITO MSM photodetectors was 0.36, 3 and 4.25 orders, at 5 V bias, respectively.