Degradation of PIN diode characteristics owing to displacement damage from low-fluence neutron exposure

Abstract

This study examines the degradation characteristics of BPW34 PIN diodes under low-fluence neutron irradiation, with a focus on displacement damage mechanisms affecting their performance. Using G4SEE simulations, the effects of neutron-induced nuclear interactions were analyzed, and non-ionizing energy loss (NIEL) calculations were validated against SR-NIEL (a web-based radiation damage calculator) values, confirming the accuracy of the G4SEE simulation. Experimental results are analyzed to show the significance of dark current and carrier lifetime of minority carriers due to displacement damage. A near-linear relationship between fluence and dark current change (ΔI) observed beyond 2 × 10⁸ p/cm² is observed. The rate at which the carrier lifetime of the semiconductor is degraded by irradiation known as carrier lifetime damage coefficient, is measured to be 5 × 10⁴ s/cm², supporting the displacement damage mechanism. Comparison of our findings with the previous reports on high fluence shows different behavior. These findings show the inability to extrapolate the high fluence degradation trend to the low fluence case, and the latter is usually encountered in practical environment, and underscores the necessity of a detail study of the impact of low fluence neutron irradiation on PIN diodes for their dosimetry applications. Here high fluence irradiation refers to fluence above 10¹² p/cm², and low fluence irradiation refer to fluence below 10⁹ p/cm².