Voltage-tunable Dual-band Infrared Photodetectors With Si/sige Metal-semiconductor-metal Heterostructure

摘要

A simple and low-cost structure of voltage-tunable dual-band near-infrared photodetector (PD) has been proposed, in which the PDs were developed by using Si_(0.8)Ge_(0.2)/Si metal-semiconductor-metal (MSM) heterostructure. The Si_(0.8)Ge_(0.2)/Si layers were deposited by ultrahigh-vacuum chemical vapor deposition system and a transparent layer of indium-tin oxide (ITO) was used as a metal layer to enhance the entrance of photons. In this study, we found that only one band was detected with a peak wavelength located at 950 nm at zero applied bias. When bias was increased to 1 V, in contrast a dual-band was achieved, where two peak wavelengths were centered at 950- and 1150-nm. It is suggested that the two bands are the absorption of top-Si and bottom-Si_(0.8)Ge_(0.2) layers, respectively. The spectra of Si bulk and Si_(0.8)Ge_(0.2) layer were also measured to verify our results and relating mechanisms are explained here.