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Strain-induced changes in the electronic valence-band structure of a cubic CdS(100) film

1991; American Physical Society; Volume: 44; Issue: 19 Linguagem: Inglês

10.1103/physrevb.44.10965

1095-3795

David W. Niles, Hartmut Höchst,

Semiconductor Quantum Structures and Devices

High-resolution angle-resolved synchrotron-radiation photoemission spectroscopy was used to determine valence-band splittings and energy-dispersion changes in a strained, cubic CdS film grown by molecular-beam epitaxy on GaAs(100). Reflection high-energy electron-diffraction patterns indicate that the biaxial in-plane surface strain is initially compressively strained by \ensuremath{\epsilon}\ensuremath{\sim}3.1%. With increasing film thickness the overlayer starts to relax, leveling off at \ensuremath{\epsilon}\ensuremath{\sim}1.0% for a 170-\AA{}-thick film. From photoemission spectra taken along the normal to the (100) surface, we measured the strain-induced splitting and modification of the energy dispersion of the CdS electronic valence bands along the \ensuremath{\Gamma}X direction. A comparison of the experimentally determined valence-band structure of the strained CdS film is made with a calculation based on the empirical pseudopotential method. The experiment verifies our theoretical prediction that strain shifts the more strongly dispersive splitoff band by \ensuremath{\Delta}E\ensuremath{\sim}0.34 eV to higher binding energy, away from the upper valence band.