Effect of V/III ratio and temperature dependence of carrier concentration in partially ordered and disordered Ga0.52In0.48P grown on GaAs substrates

We report the molecular beam epitaxial (MBE) growth of high quality In1-xGa xP epilayers grown on GaAs (0 0 1) substrate using a valved phosphorus crac ker cell. Film characterization was carried out using low-temperature photo luminescence (PL), X-ray diffraction (XRD) and variable temperature Hall ef fect measurements. The PL peak energy increased from 1.941 to 1.967 eV whil e the PL full-width at half-maximum (FWHM) decreased from similar to 11.3 t o similar to 6.3 meV as the V/III ratio was increased from 5 to 50, suggest ing an increase in atomic disorder (more random) and improvement in the opt ical quality. Temperature-dependent electron concentration data of four GaI nP samples were analyzed and fitted theoretically to deduce two levels of a ctivation energy which can be correlated to the relative ordering determine d by separate photoluminescence (PL) measurements. The activation energies, E-a1 and E-a2, increased following an increase in the ordering parameter, an effect which could be related to the potential barrier between the order ed and disordered domains, and the possible presence of native defects. (C) 2000 Elsevier Science B.V. All rights reserved.