Characteristics of GaAs/AlAs superlattice structures grown on (311) oriented GaAs substrates by molecular beam epitaxy

We report an investigation using X-ray diffraction (XRD) and photoluminescence (PL) of the crystalline and optical properties of GaAs/AlAs superlattice structures grown on (311)A GaAs substrates by molecular beam epitaxy (MBE). The results are compared with similar measurements done on identical structures grown on (100) GaAs substrates. Whereas the XRD measurements showed comparable crystalline quality in the samples grown on (311)A and (100) substrates, the PL linewidth of the (311)A samples are higher than that of the (100) samples. The PL linewidth increases linearly with rise in the temperature and the PL peak energy exhibits a significant redshift at temperatures exceeding 40 K. The PL peak energy variation with temperature of the (311)A samples showed a behaviour which is characteristic of carrier localisation by exhibiting an almost constant redshift of about 11 meV up to 300 K relative to the (100) sample.