The influence of high-energy alpha-particle irradiation on the spectral and defect properties of a Si photovoltaic detector

In this study the influence of 5.4 MeV alpha-particle irradiation on the performance of a Si photovoltaic detector, designed for system positioning, was investigated. The responsivity of the detector at 900 nm was reduced from 0.59 A W-1 for the unirradiated detector to 0.23 A W-1 for a detector which was irradiated with an alpha-particle fluence of 4.34 x 10(11) cm(-2). Using deep-level transient spectroscopy (DLTS) and current-voltage measurements (I-V) the influence of alpha-particle irradiation on the defect and electrical properties of the detectors was monitored. The electro-optical characterization was performed using an optical characterisation test station. From this preliminary investigation it would seem that alpha-particle irradiation definitely degrades the spectral response of a system-positioning photovoltaic detector. This irradiation introduces electron and hole defects in the bandgap, which have a detrimental effect on the electrical properties (reverse leakage current, dynamic resistance and ideality factor) of the junction.