Scanning tunneling microscopy and spectroscopy of Se and Te nanorods

Se and Te nanorods obtained by a self-seeding solution growth process have been examined by scanning tunneling microscopy and spectroscopy (STM/STS). The diameters of the rods, as revealed by STM images were in the range of 10–60 nm, with aspect ratios of 10–20. The I–V data of the Se and Te nanorods exhibit band gaps of ∼1.3 and ∼0.4 eV, respectively, nearly independent of the diameter, and these values are close to the bulk values of Se and Te. In both the cases, the nanorods possess a small but finite conductance even in the band gap regions, the conductance value increasing with the diameter of the rod. A tunneling mechanism involving the surface states is proposed to explain this phenomenon.