Valence band anticrossing in mismatched III‐V semiconductor alloys

The valence band anticrossing model (VBAC) is applied to explain the composition-dependent trends in dilute GaSbxAs1–x and GaBixAs1–x alloys. Photomodulated reflectance spectroscopy (PR) of GaSbxAs1–x shows a reduction of the fundamental bandgap energy as well as an increase of the spin-orbit splitting energy with increasing x. The VBAC model predicts that these shifts are the result of a hybridization of the extended valence band states of GaAs with the localized states of the impurity atoms, which induce an upward movement of the valence band edge. Extrapolation of the model to other III-(Sb,Bi)-V alloys is also discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)