PHOTOLUMINESCENCE SPECTRA OF GAP ALP SHORT-PERIOD SUPERLATTICES UNDERHIGH MAGNETIC-FIELDS/

Photoluminescence spectra in a series of GaP/AlP short-period superlat tices were measured under high magnetic fields up to 40 T in the Farad ay and the Voigt configurations. A large dependence of the photolumine scence intensity upon the magnetic-field direction relative to the sup erlattice layers was found. Namely, in the Faraday configuration, the peak intensity decreased dramatically with increasing applied magnetic field perpendicular to the superlattice layers, whereas in the Voigt configuration, a slight intensity enhancement was observed for almost all the samples. This large anisotropy in the magnetic field dependenc e of the photoluminescence intensity may be explained on the basis of a model assuming a crossover between two closely located conduction ba nds, the folded X(Z) (Gamma) states and other bands such as unfolded X (XY) or Z states, which have different cyclotron masses.