TRANSIENT RECOVERY OF MINORITY-CARRIER LIFETIME IN SILICON AFTER ULTRAVIOLET-IRRADIATION

A recovery process of minority-carrier recombination lifetime after ultraviolet (UV) irradiation has been investigated with a laser-microwave photoconductance technique for silicon wafers with native oxide. It is found that the effective lifetime which greatly increases after UV irradiation recovers to the initial value primarily with an exponential law characterized by a specific time constant called recovery time. The recovery time depends on experimental conditions where, for example, an accumulation effect of UV irradiation is observed. A mechanism of the effective lifetime recovery process is correlated mainly with the behavior of slow states associated with the silicon/native oxide interface.