Substrate-dependent electronic properties of an armchair carbon nanotube adsorbed on H/Si(001)

The adsorption of an armchair single-walled carbon nanotube (CNT) on fully and partially hydrogenated Si(001) surfaces are studied from first-principles calculations. Our results indicate that the electronic properties of the adsorbed CNT can be ruled by the H concentration along the CNT-H/Si(001) contact region. On the fully hydrogenated Si(001), the CNT is physisorbed, preserving almost unchanged its metallic character. Removing a few of H atoms along the adsorption site, we find an enhancement on the CNT metallic character. In contrast, removing all the H atoms along the adsorption site, the adsorbed CNT becomes a semiconductor, exhibiting an energy gap. These results suggest that armchair CNTs adsorbed on H/Si(001) could be transformed into metal-semiconductor junctions by grading the H concentration along the CNT-surface interface. (c) 2005 American Institute of Physics.