Reversal of spin polarization direction in excitonic photoluminescence of AlGaAsA. M. Gilinsky1, A. Winter2, C. Mejía-García2, H. Pascher2, K. S. Zhuravlev1, A. V. Efanov1, E. V. Kozhemyakina1, A. Amo3 and L. Viña3
1 Institute of Semiconductor Physics - 630090 Novosibirsk, Russia
2 Experimental Physik I, University of Bayreuth - D-95447 Bayreuth, Germany, EU
3 Departamento de Física de Materiales, Universidad Autónoma de Madrid - E-28049 Madrid, Spain, EU
received 6 September 2009; accepted in final form 25 September 2009; published October 2009
published online 9 October 2009
An anomalous reversal of the direction of exciton spin polarization is found in an optical-orientation study of AlxGa1-xAs alloys. A negative degree of circular polarization of excitonic photoluminescence is observed in direct-gap AlGaAs under excitation with circularly polarized light with the photon energy lying in a narrow range just above the free-exciton transition. The resonant switching of the polarization direction is attributed to the effect of the minor residual strain in the epitaxial film that results in lifting of the degeneracy of the light-and heavy-hole sub-bands. The electron g-factor is estimated from combined time-resolved and Hanle-effect data and amounts to 0.056–0.086 for x = 15% alloy.
72.25.Rb - Spin relaxation and scattering.
78.30.Fs - III–V and II–VI semiconductors.
78.55.-m - Photoluminescence, properties and materials.
© EPLA 2009