Electroreflectance Spectroscopy of Ga-Group V Semiconductors Using Synchrotron Radiation

David W. Lynch

《Chinese Journal of Physics》 15卷2期 (1977/07) Pp. 132-140

並列摘要

Synchrotron radiation from the 240 MeV electron storage ring Tantalus I has been used as as a light source for the electrorefiection spectroscopy of Gap, GaAs, and GaSb in the 5-30 eV energy range. After a brief discussion of the characteristics of synchrotron radiation, we discuss the spectra /in the 20-25 eV region arising from the excitation of Ga 3d electrons to various conduction band minima. These small field third derivative spectra exhibit little anisotropy, unlike those produced by valence band excitations. For Gap, the line shape of a single spin-orbit component has been fitted with Blossey.s theory, obtaining an exciton rydberg of 160MeV and an exciton broadening parameter of 160MeV. A comparison of the electroreflectance spectra with those obtained by x-ray-induced photoemission gives a core exciton rydberg of 170MeV for Gap, and 90 MeV for both GaAs and GaSb. These values are larger than the effective mass values, but not so mnch that effective mass model is invalid as a zero-order approximation. In GaAs, the transitions to the conduction band minima at f, X, and L have been identified and the L minimum is found to be lower than that at X, contrary to the conventional ordering. The temperature dependence of the transitions can be accounted for by the temperature dependence of only the conduction band final states.