Temperature-Dependent Tip-Induced Motion of Ga Adatom on GaAs (110) Surface.

The temperature-dependent tip-induced-motion of a Ga adatom on a GaAs (110) surface is experimentally demonstrated using scanning tunneling microscopy (STM). The surface adsorption energy profile obtained by first-principle electronic structure calculations reveals that the origin of the Ga motion observed at 78 K is attributable to the tip-induced Ga adatom hopping between the most stable potential minima among the three local minima, whereas that observed at 4.2 K is attributable to the tip-induced hopping and sliding motions through the next stable minima as well as the most stable minima. Furthermore, it is shown that a slight progressive modification of the adatom motion observed only at 4.2 K resulting from repeated STM line scans is consistent with the overall picture taking account of the heating of the adatom owing to the tip current.