Deformation Potentials of the Indirect and Direct Absorption Edges of AlSb

Abstract

The splittings and shifts of the phonon-aided indirect exciton edge (${\ensuremath{\Gamma}}_{15}\ensuremath{\rightarrow}{X}_{1}$) of AlSb produced by uniaxial stresses along [001], [111], and [110] have been determined. These measurements were performed at 77\ifmmode^\circ\else\textdegree\fi{}K, using the wavelength-modulation technique. TO-phonon-assisted transitions, not reported previously, have been identified in the spectrum of the stressed materials; they yield a TO-phonon energy at $X$ of 42\ifmmode\pm\else\textpm\fi{}3 meV. These measurements have also yielded the shear deformation potentials of the ${\ensuremath{\Gamma}}_{15}$ valence band ($b=\ensuremath{-}1.35\ifmmode\pm\else\textpm\fi{}0.1$ eV and $d=\ensuremath{-}4.3\ifmmode\pm\else\textpm\fi{}0.4$ eV) and the ${X}_{1}$ conduction band (${\mathcal{E}}_{2}=+5.4\ifmmode\pm\else\textpm\fi{}0.3$ eV). The hydrostatic deformation potential of the indirect edge was found to be ${a}_{i}=+2.2\ifmmode\pm\else\textpm\fi{}0.2$ eV. Electroreflectance measurements at room temperature of the direct edge (${\ensuremath{\Gamma}}_{15}\ensuremath{\rightarrow}{\ensuremath{\Gamma}}_{1c}$) of this material under uniaxial compression along the [110] direction have also been performed. The stress-induced splitting of the ${\ensuremath{\Gamma}}_{15}$ band observed in these measurements agrees with that obtained from the indirect exciton. The hydrostatic coefficient of the direct edge was found to be -5.9\ifmmode\pm\else\textpm\fi{}1.2 eV.