Selective doping of conformal GaAs layers grown by hydride vapour phase epitaxy on Si substrates studied by spatially resolved optical techniques

High quality GaAs lavers on silicon substrates were grown by conformal grow th. In this technique, the GaAs conformal growth is initiated on the sidewa lls of GaAs seed stripes (typically 10 mum wide with a pitch of 200 mum) gr own conventionally on a Si substrate, and developed inside a cavity formed by the silicon substrate and an overhanging dielectric cap layer. The confo rmal layers were grown by hydride vapour phase epitaxy (HVPE) and doped wit h Si or Zn. The properties of these layers were studied by micro-Raman, cat hadoluminescence (CL) and micro-photoluminescence (PL). The free carrier co ncentration was obtained with a micrometric spatial resolution. Both n-type (Si) and p-type (Zn) doping was achieved, showing the feasibility of selec tive doping and p-n homojunctions. (C) 2001 Elsevier Science B.V. All right s reserved.