Abstract
We report measurements of the valence band width in compressed Ge determined from x-ray emission spectra below the Ge edge. The width of the valence band does not show any pressure dependence in the semiconducting diamond-type structure of Ge below 10 GPa. On the other hand, in the metallic -Sn phase above 10 GPa the valence band width increases under compression. Density-functional calculations show an increasing valence band width under compression both in the semiconducting phase (contrary to experiment) and in the metallic -Sn phase of Ge (in agreement with observed pressure-induced broadening). The pressure-independent valence band width in the semiconducting phase of Ge appears to require theoretical advances beyond the density-functional theory or the approximation.
- Received 9 March 2004
DOI:https://doi.org/10.1103/PhysRevLett.96.137402
©2006 American Physical Society