INFRARED-ABSORPTION BY INTERSTITIAL OXYGEN IN GERMANIUM-DOPED SILICON-CRYSTALS

The effects of germanium doping on the 30-, 1 100-, and 1200-cm-1 band s of Si-O-Si were investigated. The Si-O-Si centers, perturbed by the nearby Ge atoms, caused absorptions at largely shifted positions in ea ch band. The oscillator strengths of the 1200-cm-1 absorptions and the peak separations between the 1100-cm-1 absorptions were largely reduc ed from the corresponding unperturbed ones. Our previously obtained mo del consistently explains both of the peak energies and the oscillator strengths of these absorptions. The oscillator-strength and peak-sepa ration reduction are both ascribed to the weakening of the anharmonic coupling between the 30- and the 1100-cm-1 impurity modes which causes the 1200-cm-1 band to be their combination band.