Adsorption and Self-Assembly of Alkanethiols on GaAs (001) Surface

Adsorption of alkanethiols on GaAs (001) surface under low coverage and high-coverage conditions was studied using density functional calculations in a periodic supercell approach. The thiolate adsorption site and tilt angle are dictated by the high directionality and covalent character of S-As bond. Calculated sulfur-surface binding energies are found to be significantly different for Ga-rich and As-rich surfaces and stronger than that of thiols on gold and copper surfaces. However the desorption of thiol requires much less energy in the presence of hydrogen on the surface