Four-step Method for Growing High-quality GaAs Films on Si Substrate by Molecular Beam Epitaxy

To improve quality and repeatability of GaAs growth on Si substrate, a new method named as four-step growth was proposed by successively inserting a low temperature (LT) and a high temperature (HT) GaAs buffer layer between the GaAs nucleation layer and the normal GaAs epilayer. The grown layers through four-step method showed high quality, i.e. single domain structure, mirror-like surface even under strong white light, reduced surface roughness and less surface defects, as well as high repeatability. Even without any post-growth annealing process, a 1 m thick GaAs epilayer with root mean square (RMS) roughness of only 2.1 nm in 5 m 5 m scanning areas was obtained while the full width at half maximum (FWHM) value of the GaAs (004) peak from double crystal X-ray diffraction -scan was just 210.6 arcsec.