EXCITON PARAMETERS AND ELECTRON MINIBAND STRUCTURE OF GAAS/ALGAAS SUPERLATTICES

The linear optical properties of short-period GaAs/AlGaAs superlattices (SL) with three-dimensional conduction minibands are studied. Using spectroscopy of p-polarized reflectance at oblique incidence the enhancement of exciton resonance features and effect of lineshape inversion at Brewster angle for the first time are observed. The heavy- and light-hole exciton oscillator strength is found to decrease with shortening of the SL period. Using the optical orientation technique the splitting of electron minibands linear in wave vector is measured for the first time. An essential increase of the photoelectron spin polarization is observed in the presence of magnetic field in Faraday configuration. The magnetic field effect is described in terms of the suppression of the electron spin relaxation connected with the k-linear splitting of miniband spin states.