The temperature dependence of the surface lifetime of free antimony on InSb has been determined using 10-kV reflection electron diffraction (RHEED). A desorption activation energy was extracted from these data and found to have a value of 64.2±3 K cal/mole which is within experimental error of ΔH (sublimation) for monatomic Sb. At substrate temperatures of 280 °C, it was possible to nucleate antimony in an epitaxial relationship with (111)A- and (111)B-oriented InSb surfaces; subsequent epitaxial growth could continue at temperatures as low as 40 °C. Films of InSb were grown homoepitaxially on (111)A-, (111)B-, and (001)-oriented InSb substrates and heteroepitaxially on (001)-oriented InAs and GaAs over a wide temperature range, 280 °<T<450 °C. Surface-atom reconstructions for Sb-stabilized and In-stabilized films are identified.
Thin films of InSb-InBi solid solutions have been prepared by molecular beam epitaxy. Using in situ reflection electron diffraction, conditions for epitaxial growth of stoichiometric layers were established on (001) and (110) surfaces of both InSb and GaAs wafers. Bi is shown to modify the diffraction patterns of (001) InSb from C(8×2) and (√2×√2) 45° to (1×3). Surface residence times of Bi were found indefinitely long (≳10 min) at temperatures ?420 °C. Bi incorporation into InSb during growth by molecular beam epitaxy is strongly dependent on Bi surface concentration, and influenced by substrate temperature and surface nonstoichiometry. Secondary ion mass spectrometry depth profiling and 2.5 MeV ion dechanneling spectra showed that ∼3% Bi can be incorporated substitutionally in Sb sites, under In rich growth conditions (largest available concentration of VSb sites). Increased Bi surface accumulation and interstitial incorporation are observed under Sb-rich surface conditions and as the relative flux of Bi is increased. Excess surface Bi forms liquid alloys with excess In during growth above 280 °C which alters the incorporation. These alloys solidify on the surface of grown films on cooling. Absorption cut-off wavelengths are unaffected by interstitial Bi concentrations; however, cutoffs out to ≳9.5 μm at 77 K are observed for Bi-doped films grown under In-rich conditions.
A method using coincident rf sputtering and rf discharge decomposition is shown capable of producing single-crystal, epitaxial, nonequilibrium solid solutions of Si in GaAs with the composition of Si far exceeding the limits reported for the bulk equilibrium phase diagram. Measured values of alloy composition and lattice parameter indicate close correspondence to Vegard's law. High-temperature annealing of epitaxial films demonstrates the ultimate instability of the alloys.
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