Growth of semiconductor/insulator structures: GaAs/fluoride/GaAs (001)

Abstract

Thin single-crystal layers (∼100–2000 Å) of (001) oriented SrF2 and CaF2 have been grown onto clean MBE-grown GaAs (001) surfaces. RED patterns suggest a significant difference in the interaction of CaF2 and SrF2 with clean reconstructed GaAs (001). Three-dimensional behavior is suggested in the initial nucleation stages of CaF2 growth, although significant ordering occurs for film thickness >100 Å. Nucleation of SrF2 on c(2×8) reconstructed GaAs surfaces results in a well-ordered reconstructed (4×2) surface up to film thicknesses of ∼100 Å, after which a disordered (1×1) unreconstructed surface is apparent. GaAs has been grown onto MBE prepared fluoride surfaces. At sufficiently low growth rates on CaF2, RED patterns indicate well ordered surfaces with (4×4) reconstruction. Increased deposition rates lead to twinned GaAs growth. Photoluminescence studies of undoped GaAs layers on SrF2 reveal a relatively sharp exciton structure with a full width at half-maximum (FWHM) of 4 meV. Auger depth profile experiments suggest little or no interdiffusion between the GaAs and SrF2 layers while the presence of both Ga and As is detected in the CaF2.