TEMPERATURE-DEPENDENCE OF THE OXYGEN ABSORPTION-BAND IN ZNTE-O

Absorption measurements are made as function of temperature for the isoelectronic trap ZnTe:O. This spectrum is well separated from the intrinsic absorption and from the absorption due to other impurities. The spectra can be semiquantitatively understood using a model developed for AgBr:I. The temperature dependence of the absorption due to LO-phonon cooperation is given by approximately e-gamma-T2 where gamma can be derived from the value for AgBr:I. The fine structure of the absorption is explained and the spectral symmetry between emission and absorption is discussed in detail. The electron-phonon coupling (Huang-Rhys factor) is found to be different for different phonon modes and smaller in absorption than in emission for optical modes but the inverse is true for acoustic modes.