MOVPE growth of single monolayers of InAs in GaAs studied by time-resolvedreflectance difference spectroscopy

Using reflectance difference spectroscopy (RDS), we have obtained real-time spectroscopic data detailing the evolution of the GaAs(0 0 1) surface duri ng metalorganic vapour phase epitaxy (MOVPE) of a single InAs monolayer (ML ), and subsequent growth of a GaAs capping layer. Surface anisotropy develo pments were observed by recording multitransient spectra, at fixed energies from 1.5 to 4.9 eV, during the growth of 35 periods of an InAs(1 ML)/GaAs( 100 Angstrom) superlattice (SL). From an initial d(4 x 4)-like GaAs surface under tertiarybutylarsine (TBAs) the RDS spectrum changes rapidly to a (2 x 4)-like InAs spectrum following the deposition of 1 ML of InAs. In contra st, during the growth of the GaAs cap, the evolution to the characteristic spectrum of the GaAs growing surface occurs over several monolayers, sugges ting possible In segregation. Growth temperature effects were studied in a series of such samples produced at temperatures from 450 degrees C to 600 d egrees C. (C) 1998 Elsevier Science B.V. All rights reserved.