Radiation-Induced Energy Levels in Silicon

Abstract

Radiation‐induced energy levels in silicon have been detected, positioned, and evaluated with the help of many techniques. In this paper, the presently available body of information has been organized, summarized, and analyzed. A short historical review precedes a critical discussion of evidence recently reported for electron‐, deuteron‐, and neutron‐irradiated silicon. Three conclusions emerge from such a confrontation: (1) the energy level pattern is essentially independent of the damaging agent; (2) the pattern seems to present a remarkable symmetry with respect to the middle of the gap; (3) shallow levels close to the band edges are introduced in similar concentrations and at higher rates than the deep traps. On this basis, an attempt is made to interpret the infrared absorption and photoconductivity data of Fan and Ramdas. Problems such as those associated with the charge state of radiation‐induced defect centers are examined in the light of a novel experimental approach.