Investigation of surface passivation thin film materials for improved predictable quantum efficiency detectors

We report the preliminary results from our study of different surface passivation thin film materials and deposition processes for development of
PQEDs with excellent performance and stability at room temperature and cryogenic temperatures. Our work aims at maximizing the fixed charge
density in the dielectric and the effective minority charge carrier lifetime as well as reducing the optical absorption of the dielectric in the visible range to a negligible level. We have so far demonstrated a fixed charge density of >
5x10¹² cm² and effective lifetime of > 4 ms for p-type FZ wafers passivated with PECVD SiN_x or a stack of thermal SiO₂ and PECVD SiN_x. For n-type FZ wafers passivated with ALD Al₂O₃, we have obtained an effective lifetime of ~20 ms.