The Study of Dark Currents in HgCdTe Heterostructure Photodiodes

Abstract

Dark current is the main factor that influences photodiode performance. It should be minimal to reduce noise and ensure a high level of photoelectric parameters. In order to identify the predominant causes of generation–recombination in photodiodes based on a mercury–cadmium–tellurium (MCT) ternary compound in the given voltage range, a calculation model is proposed for dark currents caused by fundamental and other current mechanisms. The components of dark current in photodiodes based on MCT heterostructures grown by molecular beam epitaxy (MBE) and liquid-phase epitaxy (LPE) methods are determined in the reverse bias voltages range from 0 to 40 mV. In the range from 0 to 20 mV, these characteristics are reduced to the diffusion component. When the reverse bias voltage exceeds 30 mV, an increase in the Shockley–Read–Hall (SRH) generation–recombination current and tunneling current through trap levels in the band gap is observed.