Abstract
The , , , , , and optical transitions have been measured in alloys using spectroscopic ellipsometry and photoreflectance. The results indicate a strong nonlinearity (bowing) in the compositional dependence of these quantities. Such behavior is not predicted by electronic structure calculations within the virtual crystal approximation. The bowing parameters for alloys show an intriguing correlation with the corresponding bowing parameters in the system, suggesting a scaling behavior for the electronic properties that is the analog of the scaling behavior found earlier for the vibrational properties. A direct consequence of this scaling behavior is a significant reduction (relative to prior theoretical estimates within the virtual crystal approximation) of the concentration for a crossover from an indirect- to a direct-gap system.
13 More- Received 6 October 2005
DOI:https://doi.org/10.1103/PhysRevB.73.125207
©2006 American Physical Society