High Resolution Measurements of Impurity-Induced Localized Vibrational Modes in Semiconductors

摘要

The recent measurements and study of the carbon-induced localized vibrational mode (LVM) in GaAs have demonstrated that nearest neighbor isotropic frequency shifts can be observed if one uses the high resolution capability of a Fourier transform infrared (FITR) spectrometer. One major importance of such measurements lies in the use of the shifts to determine the impurity site and the formation of complexes such as dimers. This feature has been used in a detailed study of the LVM infrared absorption of Si-doped GaAs. Samples electrically compensated by electron irradiation and by Li saturation were used in the study. Bands due to SiGa, SiAs, SiGa-SiAs, 7LiGa, and SiAs-AsGa (or VGa) were studied in high resolution. In several cases the structures observed in the high resolution measurements were compared with model calculations with generally satisfactory results.