Comparison of Performance of Integrated Photodetectors Based on ZnS and ZnSe Metal–Semiconductor–Metal Photodiodes

The successful fabrication of monolithically integrated photodetectors composed of a heterojunction bipolar transistor (HBT) and a metal–semiconductor–metal (MSM) photodiode was achieved by a patterned oxide growth technique. The photoresponsivities of the ZnS and the ZnSe MSM photodiodes were 0.028 and 0.08 A/W, respectively. Comparison of the performance in terms of optical and electrical characteristics between the ZnS- and the ZnSe-based integrated photodetectors were carried out; at a bias of 5 V, the current amplification ratios were 18.2 and 20.8, respectively. The maximal measurable input optical power intensities were 273 µW for ZnS-based integrated photodetector and 94 µW for ZnSe-based integrated photodetector. This successful integration indicates the potential of the patterned oxide growth technique in the development of integrated devices based on II–VI ZnS and ZnSe compounds for short-wavelength applications.