On the mechanism of spin-polarized injection in (Ga,Mn)As/n+GaAs/InGaAs Zener tunnel diode

In the present work we have investigated the spin light-emitting diode structures based on InGaAs/GaAs quantum well and a (Ga,Mn)As dilute magnetic semiconductor as an injecting layer. The luminescent properties and the magnetic-field dependence of the circular polarization degree of the initial and annealed samples were measured. It was experimentally shown that the temperature dependence of circular polarization degree below the Curie point (∼ 110 K) is determined by the thermally activated tunnelling of bound electrons from energetically split spin-up and spin-down subbands of magnetized (Ga,Mn)As. The approximation parameters allowed us to derive the values of the spin energy splitting in (Ga,Mn)As subband and the spin depolarization during the transfer from (Ga,Mn)As to the device active region. (paper)