A molecular beam study of the adsorption of tertiarybutylarsine (TBAs) on As-rich GaAs(001) surfaces

The scattering properties of tertiarybutylarsine (TBAs) on c(4X4) 2 X 4 GaAs(001) surfaces were studied by supersonic-molecular beam scattering. Polar angle measurement showed that the scattering signal was contributed from thermal desorption of trapped molecules combined with the direct-inelastic scattering. The sticking coefficient measurement revealed that the scattering behavior was very different for c(4 x 4) and 2 x 4 initial surface reconstructions. It is concluded that TBAs molecules can non-dissociatively chemisorb on c(4 x 4) through precursor-mediated mechanism, and physisorb on 2 x 4 surface. The desorption of TBAs molecule from the chemisorbed well was observed at higher temperatures above 400 K. The activation energies of the desorption (10.9 and 7.7 kcal/mol) are small reflecting that the TBAs molecular chemisorption wells are shallow.