Charge Collection in A-Si:H/A-Si1-XCx Multilayers Photodetectors


Amorphous semiconductors have been used as thin film transistor (TFT), solar cell, phototransistors. In this paper we study the charge collected properties of a-Si:H/a-Si1-xCx:H multilayer pin photodiode. In a-Si:H pin photodiode, the photogenerated carriers can be totally collected under strong electric field under reverse bias. However, our measurements show that in the a-Si:H/a-Si1-xCx:H multilayer pin photodiode photogenerated electrons and holes drift toward the electrodes under a certain bias, the total collected charge shows no saturation with bias and exhibits a continuous increas with reverse bias. We classify that the device works at two regions. In region I, the device behaves like a photodiode. This charge collection efficiency drop from theoretical value may indicate charge capture or confinement at the interfaces and trapping at the a-Si:H potential wells. These charges trapped or confined can be released at the interface and quantum well at higher electric field. In region II, above a critical bias voltage, the device works as a breakdown diode with a series photosensitive resistor which contributes higher collection efficiency, namely optical gain greater than unity.

Meeting Name

Second Int. Conference on Thin Film Physics and Applications


Nuclear Engineering and Radiation Science

Document Type

Article - Conference proceedings

Document Version


File Type





© 1994 SPIE -- The International Society for Optical Engineering, All rights reserved.

Publication Date

01 Jan 1994