Analysis of dark current considering trap-assisted tunneling mechanism for InGaAs PIN photodetectors

Abstract

In_0.53Ga_0.47As PIN photodetectors were fabricated and their dark currents were measured. Based on the analysis of different mechanisms, a complete dark current model considering trap-assisted tunneling (TAT) mechanism under low and intermediate reverse bias is constructed by studying the electric fields and carrier generation-recombination rates. The obtained current–voltage experimental results under dark conditions are in good agreement with our simulation using this complete model. The contribution of each mechanism is investigated, and to evaluate the dominant factor deriving from Shockley–Read–Hall generation or TAT, a critical voltage ($V_{cri}$) where $I_{TAT} = I_{SRH} \approx 0.5I_{dark}$ is proposed. In addition, the effects of thickness and doping concentration of absorption layer on $V_{cri}$ are discussed in detail, from which we demonstrate that $I_{TAT}$ is the dominant component of dark current for those photodetectors operating under the reverse bias of 5 V if the thickness of absorption layer is less than 1 μm when the doping concentration is 1 × 10¹⁵ cm⁻³, or the doping concentration of absorption layer is more than 7 × 10¹⁵ cm⁻³ when the thickness is 2 μm. The effect of temperature on dark current due to TAT is also analyzed.