Properties of Si-doped, MBE-grown GaAs surfaces were studied. The doped lattice positions of Si depended on the As pressure and the state of surface reconstruction. The results show that the carrier density and Si incorporation depended on the intrinsic defects. Furthermore, Si-doped GaAs layers that were fabricated with periodic interruption of 2s for each 5ML had improved crystallinity as indicated by having sharper photoluminesccnce peaks and greater carrier densities over those samples grown without interruption. (C) 2002 Elsevier Science B.V. All rights reserved.