Improvement of thick a-Si radiation detectors by field profile tailoring

This paper reports on the application of thick ∼ 50 μm a-Si p-i-n diodes as a direct radiation detector for minimum ionizing particles which is hampered by the need to apply large bias voltages in order fully to deplete the detecting intrinsic layer, which typically contains 5-10x1014 ionizable dangling bonds per cm3. By insertion of thin p-type layers at intervals within the intrinsic layer, the required depletion voltage can be reduced by a factor of at least 1/(n+1) where n is the number of layers inserted. This principle is demonstrated for devices approximately 12μm in thickness. It is shown that electron losses within the p type layer can be kept to minimum by choice of a low doping concentration for the introduced p layers