A DFT Study of Adsorption of Gallium and Gallium Nitrides on Si(111)

Abstract

Adsorption of gallium (Ga, Ga+) and gallium nitrides (GaN, GaN+, GaN2, GaN 2 + ) on a model Si(111) surface was studied by density functional theory calculations. In total 30 structures were determined. The binding energies (corrected for basis set superposition error) of the lowest structures were found to be 2.13 for Ga, 2.39 for Ga+, 4.23 for GaN, 6.13 for GaN+, 1.90 for GaN2, and 2.13 eV for GaN 2 + . Low-lying bridged structures, with the adsorbate bridging the Si rest atom and adatom were found for the diatomic and the triatomic neutral and cationic nitrides. Moreover, for the diatomics, structures with Ga-N vertical, attached to a Si adatom or a Si rest atom were also found. From electron charge distribution analysis it is confirmed that the Si cluster acts as a pool of electronic charge resulting in the adsorbed Ga and Ga+ to have similar net charges.