OXYGEN ISOELECTRONIC IMPURITIES IN ZNTE - PHOTOLUMINESCENCE AND ABSORPTION-SPECTROSCOPY

Oxygen substituting for Te in ZnTe is an isoelectronic impurity that t raps excitons. The recombination radiation and absorption spectra attr ibuted to isolated oxygen centers exhibit a no-phonon line accompanied by emission of multiple phonons. The two resulting spectra are ''mirr or images'' of each other in energy with respect to that of the no-pho non line. Photoluminescence and absorption measurements on specimens w ith significantly higher oxygen concentration disclosed additional spe ctral features with four no-phonon lines, all displaced to Io;tier ene rgies with respect to that of isolated ox gen. Photoluminescence spect ra of the present no-phonon lines show a temperature dependence charac teristic of exchange coupling between an electron and a hole. Selectiv e excitation with photon energies less than that of the no-phonon line of isolated oxygen permitted a clear observation of the features free from the phonon sidebands of isolated oxygen. These features, includi ng phonon replicas, appear to be due to excitons bound to oxygen pairs , with different OO separations. [S0163-1829(98)03236-6].