Comprehensive Investigation of Multiplication Width and Guard Ring Influence on InGaAs/InP Avalanche Photodiode Performance

This paper presents a comprehensive evaluation of the separated absorption, graded, charge, and multiplication (SAGCM) avalanche photodiodes (APDs) through both numerical calculations and experimental measurements. A total of 135 device configurations were designed and tested to investigate the effects of multiplication width (MW), attached guard ring (AGR) thickness, floating guard ring (FGR) spacing and thickness, and the number of attached FGRs on device performance. Optimization was carried out based on breakdown and punch-through voltages with respect to gain. The impact of MW was examined across a range from 0.3 μm to 0.9 μm, with corresponding evaluations of electric field profiles, breakdown voltage, and punch-through voltage. To isolate the influence of the AGR and FGR structures, subsequent analyses were carried out with a fixed MW of 0.3 μm. Four different AGR thicknesses were experimentally tested to determine the optimal value. Additionally, three FGR spacings and three FGR thicknesses were evaluated in combination with each AGR configuration, and the impact of varying the number of FGRs was also examined. As a result of these optimizations, the device breakdown voltage was significantly improved from 43.9 V to 57.6 V while maintaining a gain of 10.