Abstract
X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated (001) surfaces of KPb2Br5, K0.5Rb0.5Pb2Br5, and RbPb2Br5 single crystals grown by the Bridgman method have been measured and fundamental absorption edges of the ternary bromides have been recorded in the polarized light at 300K and 80K. The present X-ray photoelectron spectroscopy (XPS) results reveal high chemical stability of (001) surfaces of KxRb1−xPb2Br5 (x=0, 0.5, and 1.0) single crystals. Substitution of potassium for rubidium in KxRb1−xPb2Br5 does not cause any changes of binding energy values and shapes of the XPS constituent element core-level spectra. Measurements of the fundamental absorption edges indicate that band gap energy, Eg, increases by about 0.14 and 0.19eV when temperature decreases from 300K to 80K in KPb2Br5 and RbPb2Br5, respectively. Furthermore, there is no dependence of the Eg value for KPb2Br5 upon the light polarization, whilst the band gap energy value for RbPb2Br5 is bigger by 0.03–0.05eV in the case of E‖c compared to those in the cases of E‖a and E‖b.
Published Version
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