Silicon-drift photodiodes for gamma-ray scintillator photodetection

Abstract
Silicon drift photodiodes have been developed over the last five years and are a derivative of silicon drift chambers. These devices, while lacking the position sensitivity of the silicon drift chamber, retain the qualities of low capacitance and large area. These properties make them attractive for use in applications requiring low noise high efficiency photodetection, such as for scintillation light detectors in nuclear spectroscopy. These devices might also find other uses in photonics; as replacements for silicon p-i-n photodiodes in other applications demanding low noise operation. We report on our progress in fabricating silicon drift photodiodes for use as scintillator photodetectors, specifically optimized for detecting the 550 nm emission from CsI(Tl). The design we chose to build was a square photodiode 1 cm2 in area, having the general features of that described by Avset et al. Although some technical problems have temporarily delayed us from producing working drift photodiodes, we have made some diagnostic measurements on our devices and have made observations that may be of general interest.