Photoluminescence spectra of GaP/AlP short-period superlattices under high magnetic fields

Photoluminescence spectra in a series of GaP/AlP short-period superlattices were measured under high magnetic fields up to 40 T in the Faraday and the Voigt configurations. A large dependence of the photoluminescence intensity upon the magnetic-field direction relative to the superlattice 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 dependence of the photoluminescence intensity may be explained on the basis of a model assuming a crossover between two closely located conduction bands, the folded X_Z (Γ) states and other bands such as unfolded X_XY or Z states, which have different cyclotron masses. © 1996 The American Physical Society.