Prediction of Γ-L and L-X crossovers in Ga<Subscript>x</Subscript>Al<Subscript>1-x</Subscript>Sb alloys by empirical pseudopotential method

Using empirical pseudopotential method Γ-L crossover is found for the Ga<Subscript>0.74</Subscript>Al<Subscript>0.26</Subscript>Sb. The conduction band minimum is observed to switch at the (0.87, 0, 0) point for Ga<Subscript>0.51</Subscript>Al<Subscript>0.49</Subscript>Sb which shifts to the X point for Ga<Subscript>0.21</Subscript>Al<Subscript>0.79</Subscript>Sb and remains at X leading finally to indirect band gap in AlSb. Band structure calculations for a large number of alloys are performed and bowing parameters b<Subscript>X</Subscript> and b<Subscript>L</Subscript> are proposed for the E<Subscript>X</Subscript> and E<Subscript>L </Subscript> respectively. Our findings may serve as directive to select the materials in a range of composition to examine the bowing parameters and thereby effective mass experimentally for the Ga<Subscript>x</Subscript>Al<Subscript>1-x</Subscript>Sb alloys. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007