Effects of Uniaxial Stress on the Free and Bound Exciton in GaSb at 1.7 °K

The effect of a static compressive uniaxial stress on the free and bound excitons in GaSb at 1.7 ^∘{}K has been measured using wavelength-modulated reflectivity and stresses of up to 5 ×{} 10⁹ dyn cm^-2 applied along [111], [001], and [110] directions with light polarized parallel and perpendicular to the stress axis. From the observed splittings and shifts of the free-exciton line (α), we have determined the hydrostatic- and shear-deformation potentials of the direct edge. These results are compared with those of other workers. The bound-exciton line (γ) exhibits no splitting but only an isotropic shift to higher energies with stress. The lack of splitting of this line implies that previous suggestions as to the nature of the complex giving rise to this line should be reexamined.