Short-Term Anneal of 30-MeV Electron Damage in High-Purity n-Type Silicon

Abstract

Minority-carrier lifetime and electrical conductivity measurements were used to observe short-term anneal of the primary electrically active defects produced in high-resistivity n-type silicon by 4.5-, μsec 30-MeV electron pulses. These parameters were monitored from approximately 10 msec to 10 minutes following the electron pulse. Conductivity anneal experiments were conducted over a temperature range of 200° to 340°K, and lifetime experiments from 273° to 340°K. A transient forward anneal (recovery) of minority-carrier lifetime was observed for n-type silicon over this temperature range. This material exhibited a reverse (damge growth) conductivity anneal following a 30-MeV electron pulse. The growth in carrier removal sites with time is attributed to the diffusion of isolated vacancies to form the vacancy-phosphorus complex. The dependence of the anneal time constant and initial carrier removal rate on the Fermi level position suggests that the Ȱ level of the isolated vacancy is above the center of the forbidden gap at approximately 0.39 eV below the conduction band edge