OPTICALLY INDUCED POLARIZATION ANISOTROPY IN POROUS SI

Strong surface-plane polarization anisotropy of the probe photolumines cence induced by a polarized cw pump beam has been observed in porous Si. At room temperature the effect is simultaneous with the pump and d epends strongly on its intensity. At low temperature long lived anisot ropy of the photoluminescence polarization is induced by a preliminary soaking with polarized light. Both effects are described by the selec tive excitation of nonspherical Si crystals aligned along the vector p olarization of the pumping light together with complete suppression of the photoluminescence by nonradiative Auger processes in crystals wit h an additional hole and/or electron.