Homoepitaxial ZnSe MSM photodetectors with various transparent electrodes

Homoepitaxial ZnSe metal–semiconductor–metal (MSM) photodetectors with ITO, TiW and Ni/Au contact electrodes were fabricated. It was found that barrier heights for electrons were 0.66, 0.695 and 0.715 eV for ITO, TiW and Ni/Au on the homoepitaxial ZnSe, respectively. With an incident wavelength of 448 nm, it was found that the maximum responsivities for the homoepitaxial ZnSe MSM photodetectors with ITO, TiW and Ni/Au contact electrodes were 120, 50.6 and 28.1 mA/W, which corresponds to quantum efficiencies of 33.5, 14 and 8%, respectively. For a given bandwidth of 100 Hz and a given bias of 1 V, it was found that the corresponding noise equivalent power of our homoepitaxial ZnSe MSM photodetectors with ITO, TiW and Ni/Au electrodes were 8.14 × 10−13, 1.73 × 10−12 and 9.25 × 10−13 W, respectively. Furthermore, it was found that the corresponding D* were 8.7 × 1011, 4.09 × 1011 and 7.65 × 1011 cm Hz0.5 W−1, respectively.