Photoconductivity in amorphous selenium blocking structures

Abstract Photoconductive properties of the first practical a‐Se avalanche photosensor (hole drift mobility, photocurrent response time, quantum yield of charge photogeneration and avalanche multiplication gain) have been studied. It has been shown that hole transport and avalanche multiplication mechanisms in multilayered a‐Se blocking structure used in practical photosensors are similar to those observed in a‐Se monolayers confined between insulating layers and used for the first manifestation of avalanche effect in this material by Juska and Arlauskas, phys. stat. sol. (a) 59 , 389 (1980). It is suggested that combination of high avalanche gain (up to 1000) with high quantum efficiency of charge photogeneration (almost 100%) and fast photocurrent time response (∼ 1 ns) makes a‐Se avalanche photosensor a promising candidate to replace vacuum photomultiplier tubes for application in medical radiation imaging. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)