Homoepitaxial ZnSe MIS photodetectors with SiO2 and BST insulator layers

ZnSe metal–insulator–semiconductor (MIS) photodetectors with SiO2 and Ba0.25Sr0.75TiO3 (BST) insulator layers were fabricated on ZnSe substrates. It was found that dark current densities of these MIS photodetectors were at least one order of magnitude smaller than ZnSe Schottky barrier photodetector without the insulator layers. UV-to-visible rejection ratios of these MIS photodetectors were also large, and the noise equivalent power (NEP) was 1.24 × 10−13 and 1.9 × 10−13 for the homoepitaxial ZnSe MIS photodetectors with SiO2 and BST insulator layers, respectively. The corresponding normalized detectivity (D∗) was 2.55 × 1012 and 1.67 × 1012 cm Hz0.5 W−1, respectively. These values were better than those observed from the heteroepitaxial ZnSe photodetectors prepared on GaAs substrates.