Infrared Absorption Bands in Carbon- And Oxygen-Doped Silicon

Infrared absorption measurements were made before and after low-temperature electron irradiations of silicon samples which contained either dispersed oxygen, carbon, or carbon plus oxygen. Two distinctly different centers are formed upon low-temperature irradiation depending upon the carbon and oxygen content. One center is the well-known vacancy-oxygen A-center defect (836 cm−1) and is formed in oxygen-containing silicon with a magnitude which is independent of the carbon content. The other center (922 and 932 cm−1) is formed only in silicon crystals which contain both oxygen and carbon. The results indicate that this center is formed by the trapping of a silicon interstitial at a carbon-oxygen complex.