AVALANCHE PHOTODIODES: Silicon photonics reinvents avalanche photodetectors

摘要

Monolithically grown germanium/silicon APDs have high sensitivity, low noise, and world-record gain-bandwidth product. They are also CMOS-compatible and can be used at common optical-communications wavelengths. Since avalanche photodetectors (APDs) were developed more than half a century ago, device engineers have worked to improve their performance and expand their applications into diverse new areas wherever high detection sensitivity is needed. Low noise, high gain, and large bandwidth are always desirable features for APDs, especially when they are being used as an alternative to p-i-n-type photodetectors in optical-communications. As a result, most APD research has been focused on lowering the avalanche excess noise and improving gain-bandwidth product (GBW) through material and structure optimization.