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.