Charge collection in a-Si:H/a-Si1-xCx multilayers photodetectors

T. Jing, J. C. Delgado, J. Bertomeu, J. Drewray, W. S. Hong, H. Lee, S. N. Kaplan, A. Mireshghi, V. Perez-Mendez

Research output: Contribution to journalConference articlepeer-review


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 increase 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.

Original languageEnglish
Pages (from-to)345-350
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 26 Oct 1994
Event2nd International Conference on Thin Film Physics and Applications 1994 - Shanghai, China
Duration: 15 Apr 199417 Apr 1994


  • Amorphous silicon
  • Charge collection
  • Multilayers
  • Photodiode


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