SPECTROSCOPIC DETERMINATION OF THE OPTICAL DEFORMATION-POTENTIAL CONSTANT IN SEMICONDUCTORS

The optical deformation-potential constant, otherwise inaccessible in undoped materials, is measured in CdSe by optical spectroscopy with subpicosecond time resolution. The phonon-assisted transitions from B to A excitons occur with a decay time of 0.9 ps, determined by pump-and-probe experiments. An analytic expression for the transition time is obtained. Since the Frohlich interaction is symmetry forbidden, we use a nonpolar optical Hamiltonian and extract a deformation-potential constant of d0 = 32 eV.