The Generation of an Impurity-Vacancy Pair in Silicon During Irradiation

摘要

Equations are solved for the buildup of an impurity-vacancy pair in silicon during irradiation assuming vacancy but not interstitial motion. For a given integrated flux, more pairs are shown to be produced at high than at low bombardment temperatures. When silicon interstitial as well as vacancy motion is considered, the steady-state concentration of vacancies trapped at impurities is found to be r N sub I (l+r) where r is the ratio of interstitial jump time to vacancy jump time and N sub I is the concentration of impurities. The disappearance of the pairs after the irradiation ceases is determined by the jump time of the Si interstitials. Comparison of this simple first order theory with available experiments emphasizes the need for experiments to determine the state of the Si interstitial in irradiated silicon at room temperature. Either the Si interstitial is immobile at room temperature or it is trapped by substitutional impurity atoms as Watkins suggested from experiments on Al doped samples at 4K. (Author)