Mechanisms and Models for the Suppressed Defect Dynamics in SiO2–Si Structures under High‐To‐Low Switched Dose Rate Irradiations

Abstract

Ionizing‐irradiation of Si electronic devices usually occurs under variable dose rate environments such as in the outer space. It is generally accepted that the defect dynamics in SiO2–Si structures under high‐to‐low switched dose rate (SDR) irradiation are independent, although they are different. Herein, it is clearly demonstrated that this is not true, especially for thick oxide layers. By studying the recombination rates on the oxygen vacancies of dimer and puckered configurations in SiO2, three new mechanisms under SDR irradiation are found: the low‐dose‐rate (LDR) irradiation induces a transformation of high‐dose‐rate (HDR) induced “old” centers to extra electric dipoles, which in turn significantly suppresses both the generation and conversion dynamics of “new” and P b centers under LDR irradiation. An analytic model is derived based on these new mechanisms and can consistently explain the data in the literature, which although displays remarkable nonlinearity and ripples as a function of the irradiation dose. The feasibility of the SDR technology is revisited based on these new findings, and the origin of the limitation for thick oxide layers is clarified.