TUNNELING EFFECTS UPON RESONANT-RAMAN-SCATTERING INTENSITIES IN GAAS ALAS SUPERLATTICES/

We report sharp decreases in the resonant LO Raman intensity of GaAs/A lAs superlattices at the applied electric fields where the electrons c an tunnel or transfer resonantly out of the wells. This is explained b y a reduction of the exciton dephasing lifetime (i.e., increase in hom ogeneous linewidth). In particular, we observe a sharp drop at low fie lds due to tunneling to the first electron level confined in the adjac ent well and another at high field due to transfer to the X point in t he neighboring AlAs barriers. By tuning the photon energy we study GAM MA-X transfer from different states within the inhomogeneously broaden ed exciton line.