AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA7
Dynamical Behaviors of GaCl on GaAs Surfaces by Pulsed Molecular Beam Scattering

Wednesday, November 6, 2002, 4:00 pm, Room C-108

Session: Gas-Surface Dynamics
Presenter: M. Ohashi, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: M. Ohashi, National Institute of Advanced Industrial Science and Technology (AIST), Japan
M. Ozeki, Miyazaki University, Japan
Correspondent: Click to Email
Gallium chloride (GaCl) is an important precursor in the growth of compounds containing Ga and plays an important role in halide vapor-phase epitaxy (VPE) and hydride VPE. The GaAs layer grown on a GaAs(001) substrate is completely mirror-like without surface defects, but the layer grown on a GaAs(110) substrate is slightly hazy. The cause of these results is unclear. As the initial process in GaAs epitaxial growth is defined that GaCl molecule trapped into a precursor state in GaCl/GaAs surface system, this precursor plays an important role in growth. The reason that a high quality layer can be grown on a GaAs(001) substrate but not a GaAs(110) substrate has not clarified because the dynamical behaviors in the precursor states of GaCl on these surfces, such as activation energy and desorption rate have not been clarified. We investigated the adsorption mechanism of GaCl on the GaAs(001) and GaAs(110) surfaces based on angular distribution and the temperature dependence of GaCl time of flight spectra reflected from these surfaces. These well-defined surfaces are prepared by molecular beam epitaxy system connected with molecular beam scattering apparatus. The angular distribution of reflected GaCl consists of two parts; inelastic direct scattering contribution and thermal desorption of trapped molecules on the GaAs(001) and GaAs(110) surfaces. We divided the time of flight spectra of thermally desorbed GaCl into the component with activation energies of 92 kJ/mol corresponding to GaCl trapping well on GaAs(001) 2x4 surface and the components with 54 kJ/mol on GaAs(110) 1x1 surface Trapped GaCl desorbed rabidly from the GaAs(110) 1x1 surface compared to GaAs(001) 2x4 surface. These results suggest that the interaction between GaCl molecules and GaAs surface deeply influences the quality to large grown on GaAs substrates. Most of above this work was supported by New Energy and Industrial Technology Development Organization (NEDO).