Carrier Capture Dynamics of Deep-Level Defects in Neutron-Irradiated Si With Improved Intracascade Potential

Abstract

Defect–carrier interactions, especially carrier capture of defects (defect charging), are crucial for understanding displacement damage and failure mechanisms of semiconductor devices under irradiation. A multiscale model is thus developed to study the charging behaviors of deep-level defects in neutron-irradiated semiconductors. The model combines Monte Carlo and object kinetic Monte Carlo (OKMC) simulations for defect annealing, with improved rate equations based on the Shockey–Read–Hall (SRH) theory for defect charging. Especially, the rate equations newly include the improved intracascade electrostatic potential without adjustable parameters, acquired via a proposed effective polarized region model with annealed defect distributions. This model is applied to simulate the collector of the 2N2222 n-p-n silicon (Si) bipolar transistor under pulse-neutron irradiation. We found that the decrease in electron density under irradiation results from both the reduction of effective dopant concentration and the indirect electron trapping of stable vacancy–oxygen pairs (VO) and divacancies (V2). Moreover, two important mechanisms are revealed, including the cocharging of both V2(=/−) and VO(−/0) at 130 K, which corrects the traditional knowledge of single charging of V2(=/−) and the suppressed occupation of V2(=/−) due to the intracascade electrostatic potential formed by V2(−/0) charging. It is very helpful to understand the key mechanisms of the defect–carrier interactions and resolving performance failures of neutron-irradiated semiconductors.