Transient photocurrent in hydrogenated amorphous silicon and implications for photodetector devices

The transient photocurrent of amorphous silicon photodetectors is analyzed, with emphasis on its device implications. The transient photoresponse in two types of photodetector device, photoconductor and photodiode, are compared. The difference between transient photocurrent and steady-state photocurrent is discussed. Numerical modeling is used to analyze the transient photocurrent decay. The results show that response speeds in the GHz range can be achieved in amorphous silicon photodetectors with proper device structures and proper detection schemes. Potential applications are discussed.