Etching reaction of methylchloride molecule on the GaAs (0 0 1)-2 × 4 surface

摘要

Adsorption process of methylchloride (CH_3Cl) on the GaAs (0 0 1)-2 × 4 surface was studied by a scanning tunnelling microscopy (STM) measurement. The arsenic rich 2 × 4 surface, which was prepared by molecular beam epitaxy (MBE), was exposed to a supersonic molecular beam of CH_3Cl with a kinetic energy of 0.06 eV. New bright spots appeared on the CH_3Cl exposed surface. They were largely observed at the "B-type" step edge and divided into two types according to their locations. It was suggested that new spots were due to weakly adsorbed CH_3Cl molecules without any dissociation. The adsorption mechanism of CH_3Cl molecule was also studied by an ab initio Hartree-Fock calculation, which explained the experimental results well.