Chemisorption of fullerenes on semiconductor surfaces is of current technological interest. Using ab initio density functional theory under the generalized gradient approximation, we performed extensive theoretical studies on the chemisorption of a small fullerene molecule, ${\mathrm{C}}_{28}$, on the $c(4\times 4)$ reconstructed GaAs(001) surface. The chemisorption structures and energetics at various adsorption sites, in combination of possible fullerene configurations, were carefully examined and the adsorption at the trench site with one hexagon of ${\mathrm{C}}_{28}$ facing down was found to be energetically most favorable. In all cases, we found that upon ${\mathrm{C}}_{28}$ adsorption the $c(4\times 4)$ reconstructed GaAs(001) surface undergoes considerable lattice relaxation and structural deformation of fullerene molecule also occurs. The chemisorption is dictated by the $[2+2]$ cycloaddition reaction and/or by simple electron lone pair mediated charge transfer reaction from the substrate to the fullerene molecule. It was found that the monolayer formed by the ${\mathrm{C}}_{28}$ molecules on the surface is stable and naturally porous.

• Received 5 November 2004

DOI:https://doi.org/10.1103/PhysRevB.71.195316