Reflectance-difference spectroscopy of adsorbate-covered GaAs(100) surfaces: a combined surface science and in-situ OMVPE study

Using two experimental approaches, we have examined the role of adsorbates during organometallic vapor phase epitaxy (OMVPE) and atomic layer epitaxy (ALE). One set of experiments extended the RDS database to include well-defined CaAs(100) reconstructions involving CHx adsorbates, whereas the other experiments examined the RD spectra over a wide range of OMVPE conditions. We have found that the Type III OMVPE condition present at lower temperatures and higher TMGa concentration is due to a newly discovered As-rich (1 x 2)-CH3 reconstruction. The ALE condition following the trimethylgallium exposure cycle is due to the presence of a Ga-rich (1 x 4)-CH2 reconstruction. (C) 1998 Elsevier Science B.V. All rights reserved.