Improved dual-carrier high gain impact ionization engineered avalanche photodiode

Avalanche photodiodes (APDs), which have light detection and amplification combined in a single stage, are crucial for infrared detection. They operate at a relatively high reverse bias to enable avalanche multiplication from impact ionization of electrons and holes. However, avalanche multiplication process can contribute to excess noise, which results from the non-uniformity of ionization of individual carriers. Based on McIntyre's Theory [1], one important key to minimize excess noise is to make impact ionization coefficient ratio, k, zero or infinity, which is pure electron or hole multiplication. Based on previous work [2], multiple novel dual carrier multiplication structures are simulated for the study of gain and excess noise factor. Such structures can achieve much higher gain compared to conventional APDs while minimizing excess noise factor through localization of impact ionization in thin multiplication layers.