ZnSe MSM photodetectors prepared on GaAs and ZnSe substrates

Homoepitaxial and heteroepitaxial ZnSe metal–semiconductor–metal (MSM) photodetectors were both fabricated and characterized. It was found that homoepitaxial ZnSe MSM photodetector could provide us smaller dark current and large photocurrent. With an incident wavelength of 448 nm, it was found that the maximum responsivities for the homoepitaxial and heteroepitaxial ZnSe photodetectors were 0.128 and 0.045 A/W, which corresponds to a quantum efficiency of 36 and 12%, respectively. Furthermore, it was found that we achieved the minimum noise equivalent power (NEP) of 7.6 × 10−13 W and the maximum normalized detectivity (D*) of 9.3 × 1011 cm Hz0.5 W−1 from our homoepitaxial ZnSe photodetector. In contrast, NEP and D* of the heteroepitaxial ZnSe photodetector were 2.9 × 10−12 W and 2.44 × 1011 cm Hz0.5 W−1, respectively.