Preparation, characterization and electrical transport properties of individual alpha-MnO2 and beta-MnO2 nanorods

Electrical transport experiments are performed on individual alpha-MnO2 and beta-MnO2 nanorods. Both of alpha-MnO2 and beta-MnO2 nanorods are synthesized via hydrothermal routes. A three-region method is used to analyze their nonlinear current-voltage characteristics. Under low biases, the effective contact barrier height is roughly estimated to be 0.05 eV for alpha-MnO2 and 0.15 eV for beta-MnO2, respectively. As the applied bias is high enough, the contact barriers are significantly tilted and the current is largely tunneling. The conductance of alpha-MnO2 and beta-MnO2 nanorods at room temperature is roughly estimated to be 5.98 and 1.74 x 10(-3) cm(-1) Omega(-1), respectively. And the thermal-activation energy is roughly estimated to be 0.047 and 0.226 eV, respectively. OUT results are probably the bases for their applications in nanosized electrical devices. (C) 2009 Elsevier Masson SAS. All rights reserved.