Investigation of the effect of oxygen on the cathodoluminescence spectra and band gap of the ZnS {sub x} Se {sub 1-x} alloy

Abstract:

The cathodoluminescence spectra of polycrystalline CVD ZnS{sub x}Se{sub 1-x} alloy layers grown with the Zn excess are investigated. The dependence E{sub g}(x) is refined taking into account the location of exciton bands at 300 K. It is confirmed that the spectra are reconstructed on dissolving oxygen in the lattice under the effect of high pressures and temperatures of the gas-static treatment. The dependence of the self-activated emission on the alloy composition is observed for the accepted conditions of the gas-static treatment. For the compositions close to ZnSe (x < 0.5), the self-activated SAL band emerges. In contrast with this, only the short-wavelength shift of the SA band is observed for the compositions close to ZnS (x > 0.7), which is also most typical of the compounds themselves. These specific features are interpreted based on the calculations of the equilibrium of intrinsic point defects, which affect the location of the Fermi level under the deviation of ZnSe and ZnS from stoichiometry. The spectral regions, in which the bands of oxygen-containing SA and SAL complexes in the ZnS{sub x}Se{sub 1-x} alloy can be observed, are evaluated. These regions depend on x and the oxygen concentration at the lattice sites. The behavior of exciton bands and infrared radiation emerging in the Cu (3d{sup 9}) ions is investigated after the gas-static treatment. It is shown that the variation in the ensemble of intrinsic point defects during the gas-static treatment is determined by an increase in the number of defects with a smaller volume, specifically, the S{sub Se} antisite defects. The spectra are interpreted based on the theory of nonoverlapping bands …

Año de publicación:

2006

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Fuente:

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