Configuration dependence of band-gap narrowing and localization in dilute GaAs1−xBix alloys

Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations (≤2%), in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a valence band defect level anticrossing between As and Bi occupied p levels. Predictive models for the valence band …