Surface Enhanced Silicon Avalanche Photodiodes for Near-IR Detection

This Phase II SBIR builds on the exciting results demonstrated during the Phase I research. Using a new approach for enhancing the near-infrared (IR) sensitivity of high gain avalanche photodiodes (APDs), Radiation Monitoring Devices, Inc. (RMD) will develop a reliable procedure to produce APD arrays with high sensitivity at 1064 nm. This work utilizes an innovative technique to microtexture the front surface of the APD using high power, ultra-short laser pulses (100 femto-seconds). The laser processed silicon surface exhibits remarkably high absorption characteristics over a large range of wavelengths (0.4 - 3 microns). Phase I work established that this processing technique provides an enhancement in the photo-induced charge collection at near-IR wavelengths. We have further demonstrated APD responsivity > 350 A/W at 1064 nm. Evidence of silicon bandgap transformations makes this remarkable innovation extremely promising for present detector technology needs.The ultimate goal of this project is to use laser microtexturing technology to develop a high speed, high gain, low noise APD array sensor module with significantly improved near-IR response. The APD array sensor will be an extremely valuable tool for long distance optical communication and for LIDAR/LADAR applications.