Characterization of GaAs conformal layers grown by hydride vapour phase epitaxy on Si substrates by microphotoluminescence cathodoluminescence and microRaman

Conformal growth of GaAs on Si consists of the confined lateral selective e pitaxy of GaAs from GaAs oriented seeds on silicon, the vertical growth bei ng stopped by an overhanging dielectric mask. Low defect GaAs films are obt ained due to the absence of direct nucleation of the conformal GaAs epilaye rs on Si, and to the geometrical hindrance of the propagation of dislocatio ns into the growing layer by the capping surface and by the substrate. GaAs conformal layers grown by hydride vapour phase epitaxy (HVPE) were charact erised by microphotoluminescence (MPL), cathodoluminescence (CL) and microR aman. The GaAs conformal layers were found of superior quality since their luminescence emission was enhanced by several orders of magnitude with resp ect to the seeds directly grown on the Si substrate. CL and MPL images reve aled in plane modulation of the luminescence emission. This modulation was associated with residual stress. MicroRaman measurements revealed stress di stribution and eventually local symmetry breakdown. (C) 2000 Elsevier Scien ce B.V. All rights reserved.