Electronic structure of GaxAl1-xSb alloys by empirical pseudopotential method

Electronic band structure calculations are reported for the Ga_xAl_1-xSb alloys using empirical pseudopotential method within the virtual crystal approximation. The calculations show that the system of Ga_xAl_1-xSb alloys consists of multiple valley conduction bands. The Gamma-L crossover is found for the Ga_0.74Al_0.26Sb alloy well in agreement with the experimental findings. The conduction band minimum (CBM) has been observed to switch at the (0.87,0,0) point for Ga_0.51Al_0.49Sb. The CBM shifts to the X point for Ga_0.21Al_0.79Sb alloy and remains at X leading Anally to indirect band gap in AlSb. The calculations have been used to report bowing parameters E_X and E_L for the alloys. Our findings may be useful to select the materials in a range of composition to examine the bowing parameter E_X and effective mass experimentally to design low dimensional quantum systems. Refractive indices for all the alloys are also calculated for possible comparison with experiments to appear in future.