Dependence of the hole lifetime on uniaxial stress in Ga-doped Ge

The effect of uniaxial stress on the hole lifetime in gallium-doped germanium single crystals has been studied by photo-Hall-effect measurements. We demonstrate that the stress dependence of the hole lifetime offers a critical test for competing models of the capture of holes by acceptors. We find that below 5 K the hole lifetime increases by over one order of magnitude upon the application of 4 kbar in a [l angle]100[r angle] direction. Our results show the hole lifetime to be proportional to the acoustic-phonon-scattering component of the hole mobility, in very good agreement with the cascade capture theory for Coulomb-attractive centers and in clear contradiction to the recently proposed model in which holes are directly captured into the acceptor ground state [Phys. Rev. Lett. [bold 69], 2839 (1992)].