Enhanced broadband photodetection in ZnO/black silicon heterojunctions from ultraviolet to short-wave infrared

Abstract

Broadband photodetectors hold significant application potential across diverse fields, including optical communications, environmental monitoring, and military surveillance systems. This study presents the development of a zinc oxide/black silicon (ZnO/b-Si) heterojunction photodetector with broadband detection capability spanning from ultraviolet (254 nm) to short-wave infrared (1550 nm). ZnO films were deposited via magnetron sputtering on textured argon-hyperdoped b-Si substrates, followed by systematic optimization of sputtering parameters and post-annealing to improve crystallinity. Structural and optical characterization confirmed the preparation of the ZnO films, with a preferred (002) orientation and a bandgap of 3.29 eV after annealing. The ZnO/b-Si heterojunction demonstrated broadband photo response, with responsivities of 3.73 mA/W (365 nm), 530.4 mA/W (780 nm), and 40.09 mA/W (1550 nm) under forward bias of 6 V. This work highlights the potential of ZnO/b-Si heterostructures for cost-effective, broadband photodetection in advanced optoelectronic applications.