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

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 (V-2). Moreover, two important mechanisms are revealed, including the cocharging of both V-2(=/-) and VO(-/0) at 130 K, which corrects the traditional knowledge of single charging of V-2(=/-) and the suppressed occupation of V-2(=/-) due to the intracascade electrostatic potential formed by V-2(-/0) charging. It is very helpful to understand the key mechanisms of the defect-carrier interactions and resolving performance failures of neutron-irradiated semiconductors.