Dark Currents in HgCdTe Photodiodes Passivated with ZnS/CdS

Abstract

Experimental and theoretical results are presented for current‐voltage and dynamic resistance‐voltage characteristics of ion‐implanted p‐n junction photodiodes with ≈ 0.22 passivated with ZnS/CdS layers. By measuring the temperature dependence of the dc characteristics in the temperature range 25–140 K the dark current mechanisms are studied and the validity of the modeling is confirmed. It was found that the dark currents can be represented with three current components over a broad range of voltage and temperature. At high temperature (>90 K) and in low reverse bias region, the diffusion current dominates. On the other hand, at medium temperature (40–80 K) and medium reverse bias (< −0.15 V), trap‐assisted tunneling plays an important role. At low temperature (<40 K) and in the medium reverse bias region (> −0.15 V), band‐to‐band tunneling is the key leakage current source. However, when the temperature is further lowered to 25 K and the applied reverse bias is very small (−0.15 to 0 V), the band‐to‐band tunneling current will be ruled out and the trap‐assisted tunneling mechanism dominates again. © 1999 The Electrochemical Society. All rights reserved.