Abstract
The surfactant effect of atomic hydrogen on the incorporation of silicon into (100)-, (111)A-, and (311)A-oriented GaAs grown by hydrogen-assisted molecular beam epitaxy has been studied with Raman spectroscopy. Local vibrational modes (LVMs) of SiGa and SiAs impurities are observed for excitation nearly resonant with the E1 energy gap. Site switch of the doping Si atoms from Ga to As lattice sites due to the surfactant effect of H during growth of the high-index doped layers was directly monitored by changes of the normalized intensity of the LVMs. An increase of the free carrier concentration in p-type samples and a decrease in n-type samples resulting from this site switch were also observed in the plasmon-phonon coupled modes as observed in Raman scattering. Similar changes in carrier concentrations were observed by means of electrical transport measurements.
Published Version
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