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Study of Reflection High-Energy Electron Diffraction Oscillation for Optimization of Tertiarybutylphosphine-Based Molecular Beam Epitaxial Growth of In0.48Ga0.52P on GaAs

A detailed study of reflection high-energy electron diffraction (RHEED) oscillation was made for the tertiarybutylphosphine (TBP)-based gas-source molecular beam epitaxial (GSMBE) growth of In1-xGaxP on GaAs in order to obtain lattice-matched layers (x=0.52) with high electrical qualities. For growth of InGaP on conventional As-rich c(4×4) GaAs surfaces obtained by cooling under As4 flux irradiation after GaAs growth, no RHEED oscillation was observed. On the other hand, by growing InGaP layer on As-stabilized (2×4) GaAs surfaces obtained by exposure to low As4 pressures, clear and persistent RHEED oscillations were successfully observed for the first time. Growth under a sufficient TBP flow rate with careful adjustment of the substrate temperature within a narrow range was found to be important for realizing stable layer-by-layer growth of InGaP layer and for obtaining high-quality layers. The optimal InGaP layers achieved minimum full-width at half maximum (FWHM) values of X-ray diffraction (XRD) and photoluminescence (PL) peaks of 18 s and 15.5 meV, respectively. Nondoped layers grown under the optimal conditions realized high electron mobility values of 3,300 cm2/Vs at 300 K and 21,000 cm2/Vs at 77 K with low residual carrier concentration values of 5×1014–5×1015 cm-3. These are the best values reported so far for InGaP layers grown by GSMBE using TBP and are comparable to the best values reported so far for InGaP layers grown by other methods.