Preferential orientation of a chiral semiconducting carbon nanotube on the locally depassivated Si(100)-2 × 1:H surface identified by scanning tunneling microscopy

Nanoscale depassivation of the Si(100)-2× 1:H surface with the UHV STM served to locally stabilize an isolated s-SWNT, initially sensitive to the rastered STM tip due to a weak coupling with the supporting substrate. The identification of the s-SWNT was enabled by atomically resolved imaging such as STM height measurements and tunneling spectroscopy. Spatially resolved I-V spectra revealed a slight compression and p-type shift of the s-SWNT bandgap on depassivated Si. An atomic model of the tube consistent with the experimental geometry verified the parallel alignment of the zigzag direction on the bottom side of the tube with the dimer rows. Further atomistic experimental and theoretical studies are needed to conclusively establish the formation of C-Si covalent bonds at the interface between the selectively depassivated Si(100) surface and such preferentially oriented ≊1 nm-diameter chiral s-SWNTs.