Low-Noise, Temperature-Stable, Digital Alloy Avalanche Photodiodes
Avalanche Photodiodes (APDs) have been widely deployed in commercial, scientific, and military applications, including use in data center receivers, LIDAR detectors, and hyperspectral imaging cameras. APDs provide an intrinsic gain to absorbed optical signals, resulting in higher receiver sensitivity than traditional P-I-N photodiodes. This internal gain mechanism arises from the process of impact ionization. The stochastic nature of impact ionization creates fluctuations in the amplified signal and thereby creates excess noise, which is quantified by an excess noise factor, F(M).
We have demonstrated extremely low excess noise in the AlxIn1-xAsySb1-ydigital alloy material system, comparable to that of silicon. Furthermore, AlxIn1-xAsySb1-yexhibits a low avalanche breakdown temperature dependence, making it an ideal material system for detector applications in variable ambient conditions. Thirdly, AlxIn1-xAsySb1-yboasts a wide bandgap tunability, from 0.25 to 1.3 eV, primarily as a change in the conduction band. This final factor allows for the application of these superior performance characteristics in complex APD band structures, serving as a gateway to new approaches in low-noise, temperature-stable photodetection.