3D Hopping Conduction in SnO2 nanobelts
  The temperature dependence of the electrical transport of a individual tin oxide nanobelt was measured, in darkness, from 400 to 5K. We found four intrinsic electrical transport mechanisms through the nanobelt. It starts with Thermal-Activation Conduction between 400 and 314K, Nearest-Neighbor Hopping conduction between 268 and 115K, and Variable Range Hopping conduction below 58K, with a crossover from the 3D-Mott to the 3D-Efros-Shklovskii regime at 16K. We claim that this sequence reveal the three-dimensional nature of the electrical transport in the SnO2 nanobelts, even they are expected to behave as one-dimensional systems. 
E. R. Viana, J. C. Gonzalez, G. M. Ribeiro and A. G. de Oliveira
cond-mat.mes-hall cond-mat.mtrl-sci