Modulation-spectroscopy study of theGa1−xAlxSbband structure

We report a detailed study of the ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{Sb}$ band structure over the entire composition range. We have determined the energies, as a function of temperature, at which the direct transitions ${\Gamma }_8^v\to {\Gamma }_6^c\left(E_0\right)$, ${\Gamma }_7^v\to {\Gamma }_6^c(E_0+{\Delta }_0)$, $L_{4,5}^v\to L_6^c\left(E_1\right)$, and $L_6^v\to L_6^c(E_1+{\Delta }_1)$ occur, and those at which the indirect transitions ${\Gamma }_8^v\to X_6^c\left(E_X\right)$ and ${\Gamma }_8^v\to L_6^c\left(E_L\right)$ occur. A simple physical model is proposed to explain the experimental values of the $E_0$, ${\Delta }_0$, $E_1$, ${\Delta }_1$ bowing parameters. A detailed comparison is made between our results and previously reported ones.