Effect of oxygen doping on the IR transmission and cathodoluminescence of ZnSe

The effect of oxygen doping (0.9 and 4.3 Vol % O-2 in the gas phase) on the transmission and cathodoluminescence of CVD ZnSe was studied. The incorporation of oxygen was found to reduce the transmission in the spectral range 700-1900 cm(-1). Examination by scanning electron microscopy shows that Se excesses and high O-2 concentrations lead to tabular growth. ZnO precipitation at structural defects during cooling was observed only in the end portion of the deposit. The dimensions of microinhomogeneities are shown to have a significant effect on the transmission of ZnSe. The oxygen-containing species present in the deposits were identified using cathodoluminescence spectra. The CL spectrum of Se-enriched p-type ZnSe is dominated by the band at 490 nm (SAL) at 80 K and the band at 640 nm (SA) at 300 K. The 640-nm band is attributed to recharging of the SAL centers upon a variation of the Fermi energy with temperature. Decreasing the Se excess leads to the quenching of the SAL emission and appearance of the shorter wavelength component of the SA band at 600 nm (80-300 K), characteristic of slightly Zn-enriched ZnSe. The intensity of the self-activated bands is shown to increase as the concentration of dissolved oxygen increases.