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Nature of the Band Gap of In 2 O 3 Revealed by First-Principles Calculations and X-Ray Spectroscopy

2008; American Physical Society; Volume: 100; Issue: 16 Linguagem: Inglês

10.1103/physrevlett.100.167402

1092-0145

Aron Walsh, Juarez L. F. Da Silva, Su‐Huai Wei, Christoph Körber, Andreas Klein, Louis F. J. Piper, A. DeMasi, Kevin E. Smith, G. Panaccione, Piero Torelli, David J. Payne, A. Bourlange, R.G. Egdell,

ZnO doping and properties

Bulk and surface sensitive x-ray spectroscopic techniques are applied in tandem to show that the valence band edge for ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ is found significantly closer to the bottom of the conduction band than expected on the basis of the widely quoted bulk band gap of 3.75 eV. First-principles theory shows that the upper valence bands of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ exhibit a small dispersion and the conduction band minimum is positioned at $\ensuremath{\Gamma}$. However, direct optical transitions give a minimal dipole intensity until 0.8 eV below the valence band maximum. The results set an upper limit on the fundamental band gap of 2.9 eV.