GaN Ultraviolet Photodetectors with Transparent Titanium Tungsten and Tungsten Electrodes

GaN metal-semiconductor-metal (MSM) ultraviolet photodetectors with titanium tungsten (TiW) and tungsten (W) transparent electrodes were fabricated and characterized. It was found that the -thick TiW and W films could provide a reasonably high transmittance of 78 and 65.4% at , a low resistivity of 1.7 and , and an effective Schottky barrier height of 0.773 and on u-GaN, respectively. We also achieved a peak responsivity of 0.192 and , a quantum efficiency of 66.4 and 51.8% from the GaN UV MSM photodetector with TiW and W electrodes, respectively. With a applied bias, the noise equivalent power of photodetectors with TiW and W electrodes were estimated to be and , corresponding to the normalized detectivity of 6.36 and , respectively.