A highly sensitive a-Si photodetector array with integrated filter for optical detection in MEMS

This paper presents a highly sensitive photo-detector array deposited on a glass substrate with an integrated optical filter. The active element is a vertically integrated hydrogenated amorphous silicon photodiode featuring a dark current of less than 1e-10 A/cm2 for -3V bias voltage and a maximal quantum efficiency of 80% near 580 nm. The prototype was encapsulated and tested optically. It has a fill factor of only 44% which, however, can be easily increased to 90% using flip-chip bonding to an integrated electronic circuit for signal conditioning. The sensor is bio-compatible and can be integrated with other glass-based MEMS devices.