Abstract
In the field of near-infrared weak light detection, an InP/InGaAs single-photon avalanche diode (SPAD) is preferred due to the advantages of high sensitivity, low cost and room-temperature operation. To properly simulate and optimize the SPAD’s front-end circuit, a comprehensive and compact behavior model of the InP/InGaAs SPAD is normally required to accurately describe the statistical behavior of the detectors. In this paper, an InP/InGaAs SPAD analytical model is constructed, which not only includes the direct current (DC) and alternating current (AC) behavior simulating the avalanche and quenching processes, but also describes the dark count, after-pulsing and photon detection efficiency. For dark count noise, three important generation mechanisms are considered, including thermal generation, trap-assisted tunneling and band-to-band tunneling. The model described by the Verilog-A hardware description language (HDL) can be directly implemented in the commercial circuit simulator. A gated mode, passive quenching and recharging circuit is used to simulate and verify the developed model. The simulation results are in good agreement with the reported test data, demonstrating the accuracy of the developed InP/InGaAs SPAD model.
Highlights
As an important weak light detection technology, single-photon detection has been widely used in numerous applications, such as high-resolution, three-dimensional (3D) imaging [1], quantum information processing [2], astronomical exploration [3] and spectrum resolution [4]
When an InP/InGaAs single-photon avalanche diode (SPAD) with an SAGCM structure operates in Geiger mode, a self-sustaining avalanche current may be triggered by the carriers generated by photon absorption, or other excitation mechanisms, and keeps flowing until the applied voltage across the SPAD is lowered below the breakdown voltage Vbrk
The total direct current (DC) generated by these paths was denoted as ISPAD, and the alternating current (AC) behavior was modeled by three capacitors marked as CJ, CKS and CAS
Summary
As an important weak light detection technology, single-photon detection has been widely used in numerous applications, such as high-resolution, three-dimensional (3D) imaging [1], quantum information processing [2], astronomical exploration [3] and spectrum resolution [4]. The generation mechanisms and contributions of dark carriers are apparently different from that of Si-based SPADs. To obtain optimal device performance, many theoretical models have been established to analyze the characteristics of InGaAs/InP SPADs. For example, Donnelly et al [8] presented an experimental model to predict the dark count rate (DCR) and photon detection efficiency (PDE), but after-pulsing was not considered. There are many dark carrier generation mechanisms in an InP/InGaAs SPAD, the dominant contributions to the DCR [17] are as follows: (1) generation–recombination in the depletion region; (2) band-to-band tunneling (BTBT); Electronics 2020, 10, x FOR PEER REVIEW charge layers were much smaller than those of the absorption and the multiplication regions, the dark count in these two layers was neglected for simplicity.
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