Charge-layer design considerations in SAGCM InGaAs/InAlAs avalanche photodiodes

Abstract

We report on the development of mesa-processed InGaAs/InAlAs avalanche photodiodes (APDs) for short-wave infrared (SWIR) imaging applications with demand for high gain and low breakdown voltage. Devices are designed with separate absorption, grading, charge, and multiplication (SAGCM) layers. Special attention has been paid to the charge layer in order to optimize the structure for low band discontinuities and an appropriate electric field distribution. Hereof, a combination of a p-type grading layer and charge layer is presented. Band-edge profile calculations as well as electro-optical characterization results of the APDs will be discussed in this article. Our optimized APD structures reveal low punch-through and low breakdown voltage of V-pt approximate to 8.5 V and V-bd approximate to 2.3 V, respectively. A maximum gain of M > 300 in the linear operation mode is demonstrated at room temperature and M = 10 has been measured at 20 V bias

Optimized Selective‐Area p‐Type Diffusion for the Back‐Illuminated Planar InGaAs/InP Avalanche Photodiodes by a Single Diffusion Process

“…[ 5,6 ] It has been proven that planar InGaAs/InP APDs exhibited lower leakage current, higher stability, and higher reliability compared with mesa‐type ones. [ 7–9 ] Selective‐area zinc diffusion technique has been thus developed as an effective way to obtain p‐type InP layers for planar InGaAs/InP APDs. There were several methods to realize selective‐area zinc diffusion in InP layers, mainly including chamber diffusion by metal‐organic chemical vapor deposition (MOCVD) using dimethylzinc (DMZn) or diethylzinc (DEZn) as the p‐type dopant [ 10,11 ] and furnace diffusion with ZnP 2 or Zn 3 P 2 in a sealed or semiclosed or open quartz ampoule.…”

Theoretical Analysis of InGaAs/InAlAs Single-Photon Avalanche Photodiodes

“…Thus, a suitable electric-field distribution is significant for InAlAs SPADs, which is determined by the charge-layer and multiplication-layer thickness. Considering the charge layer of InAlAs APDs, Kleinow et al studied the influence of doping concentration in this layer and found that doping concentration is more important for the performance of InGaAs/InAlAs APDs [25, 26]. Chen et al studied the influence of the charge and multiplication layers on punch-through and breakdown voltages by theoretical analysis and simulation [27].…”

Fabrication and Characterization of Planar-Type Top-Illuminated InP-Based Avalanche Photodetector on Conductive Substrate with Operating Speeds Exceeding 10 Gbps

“…High-speed InP-based APDs are preferred over PIN-type photodetectors [ 10 ], particularly for conventional long-haul applications. The preferred solution in these situations is the separate absorption, grading, charge, and multiplication (SAGCM) structure, due to its low dark current [ 11 , 12 , 13 , 14 ], high quantum efficiency, and high gain-bandwidth product [ 15 , 16 , 17 ]. The importance of performance and reliability in these systems [ 18 , 19 ] has prompted research on epitaxy and device processing for the further development of high-performance and high-speed planar InP based SAGCM-APDs [ 20 , 21 , 22 , 23 , 24 ].…”