Observation of enhanced infrared photoresponse in forward-biased amorphous silicon p-i-n diodes

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Abstract
The photoconductive response of hydrogenated amorphous silicon (a‐Si:H) p‐i‐n diodes has been investigated under conditions of low‐temperature operation. We show that cooled p‐i‐n diodes exhibit an enhanced infrared response when operated under forward bias conditions. The induced IR response is of the order of 10−3A/W, extending out to wavelengths of about 2–3 μm with the long wavelength cutoff being determined by the properties of the glass/indium–tin–oxide entrance window. We propose that the IR photoeffect is due to the re‐excitation of band‐tail trapped excess carriers injected into the localized conduction and valence band tail states in the vicinity of the n+‐ and p+‐contact regions.