Investigation of the Effects of the Multiplication Area Shape on the Operational Parameters of InGaAs/InAlAs SPADs

TL;DR

This study models InGaAs/InAlAs SPADs to understand how the shape of the multiplication area affects their operational parameters, revealing that smaller active regions reduce dark current and that breakdown voltage indicates device quality.

Contribution

The paper introduces a 2D model analyzing how the active area shape influences SPAD performance, highlighting the importance of breakdown voltage as a quality metric.

Findings

Reducing active region diameter decreases dark current by about 10 dB.

Breakdown voltage correlates with device quality and uniformity.

Current-voltage curves can be used to select high-quality SPADs.

Abstract

A 2D model of an InGaAs/InAlAs single photon avalanche photodiode has been developed. The influence of the active area structure in the multiplication region on the diode's operating parameters has been studied. It was found that changing the diameter of the structure's active region leads to a change in the dark current in the linear part of the current-voltage curve and a change in the breakdown voltage. Reducing the diameter of the active region from 25 $\mu$m to 10 $\mu$m allowed decreasing the dark current in the linear mode by about $10$ dB. It has been shown that the quality of the SPAD device can be assessed by knowing the avalanche breakdown voltage and the overall current-voltage curve plot if we consider structures with the same multiplication region thickness and different remaining layers. The higher the breakdown voltage, the better the structure's quality due to smaller local increases in the field strength. Following this statement, we conclude that for further use in single-photon detectors, it is reasonable to pick specific SPADs from a batch on the sole basis of their current-voltage curves.