Influence of disorder on the optical absorption in semiconductors: Application to epitaxially grown III-V compounds

The influence of disorder on optical properties of semiconductors is discussed in different models: phenomenological model of partially relaxed k-selection rule, spectral density model, and the model taking into account excitonic effects. These models were compared to experimental spectra of disordered GaAs, where disorder was generated either by MBE low temperature growth or by implantation of arsenic. Reasonable agreement between the data and the models was obtained. The analysis of the data supports the view that the main source of disorder in nonstoichiometric GaAs are the defects resulting from the excessive arsenic, e.g., arsenic antisites.