Optical orientation and spin-dependent recombination in GaAsN alloys undercontinuous-wave pumping

Abstract

We present a systematic theoretical study of spin-dependent recombination and itseffect on optical orientation of photoelectron spins in semiconductors with deepparamagnetic centers. For this aim we generalize the Shockley–Read theory ofrecombination of electrons and holes through the deep centers with allowance foroptically-induced spin polarization of free and bound electrons. Starting fromconsideration of defects with three charge states we turn to the two-charge-statemodel possessing nine parameters and show that it is compatible with availableexperimental data on undoped GaAsN alloys. In the weak- and strong-pumpinglimits, we derive simple analytic equations which are useful in prediction andinterpretation of experimental results. Experimental and theoretical dependences of thespin-dependent recombination ratio and degree of photoluminescence circular polarizationon the pumping intensity and the transverse magnetic field are compared anddiscussed.