Localization of Electronic States in III-V Semiconductor Alloys: A Comparative Study

Electronic properties of III-V semiconductor alloys are examined using first principles, with the focus on the spatial localization of electronic states. We compare localization at the band edges due to various isovalent impurities in a host GaAs, including its impact on the photoluminescence linewidths and carrier mobilities. The extremity of localization at the band edges is correlated with the ability of individual elements to change the band gap and the relative band alignment. Additionally, the formation energies of substitutional defects are calculated and linked to challenges associated with the growth and formability of alloys. A spectrally resolved inverse participation ratio is used to map localization in prospective GaAs-based materials alloyed with B, N, In, Sb, and Bi for 1.55-mu m-wavelength telecommunication lasers. This analysis is complemented by a band unfolding of the electronic structure and a discussion of the implications of localization on the optical gain and Auger losses. Correspondence with experimental data on the broadening of the photoluminescence spectrum and charge-carrier mobilities show that the localization characteristics can serve as a guideline for the engineering of semiconductor alloys.