Band structure effects on one-dimensional resonant tunneling in STM tips made of carbon nanotubes

Abstract

In recent experiments, attempts were made to use carbon nanotubes to replace the normal metal tips in the scanning tunneling microscope (STM), and stable atomic images were observed. However, does the one-dimensional characteristic band structure of the carbon nanotube (CNT) affect the tunneling? We present a theoretical analysis of the one-dimensional resonance tunneling model using the nonequilibrium Green's function method. The results clearly imply that the Van Hove singularities of the CNT probe play an important role in the tunneling process. The resonance curve is quite different from the one with a metallic tip; new peaks and peak splittings are induced. So these characteristics must be considered seriously if one uses a nanoprobe as the STM tip. We also notice that a sharp peak will appear near the first Van Hove singularity, which resembles the Kondo peak.