Enhanced Carrier Multiplication in InAs Quantum Dots for Bulk Avalanche Photodetector Applications

Exploring the potentiality of enhancing the performance of avalanche photodiodes (APDs) using novel nanoscale structures is highly attractive for overcoming the bottleneck of avalanche probability. This work demonstrates, for the first time, multiplication enhancement of electron-initiated photocurrent due to impact ionization in InAs quantum dots (QDs) within a GaAs APD structure. A five-layer stacked 2.25 MLs InAs QD/50 nm GaAs spacer multiplication structure integrated into a separated absorption, charge, and multiplication GaAs homo APD results in up to six times higher multiplication factors in comparison to a reference device without QD over a temperature range of 77-300 K. In addition, extremely low excess noise factor in close proximity to that of silicon is also observed with an effective k(eff) factor below 0.1. This demonstration is of fundamental interest and relevant for future ultra efficient avalanche detector applications.