Mitsutoshi Honda

Electrical Properties of Anodically Oxidized Nb2O5 and Si-Doped Nb2O5 Films

The basic electrical properties of Nb2O5 and Si-doped Nb2O5 (Nb2O5–Si) thin films, which were obtained by anodically oxidizing Nb in an H3PO4 solution, were investigated using their current–voltage (I–V) and capacitance–voltage (C–V) characteristics with the aim of determining their electrical conduction mechanism. In the forward bias condition, Poole–Frenkel conduction is plausible for both Nb2O5 and Nb2O5–Si (Si-doping less than 19 at. %). For the reverse bias condition, a Schottky-barrier is formed at the Au/Nb2O5 and/or Au/Nb2O5–Si interface (Si-doping less than 5 at. %) because of the difference in the work function. The low frequency capacitance (1 kHz) increased with forward bias due to the lifetime of the carriers (electrons, holes, or both) injected into the Nb2O5 and/or Nb2O5–Si films. A schematic energy band diagram for Au/Nb2O5/Nb and/or Au/Nb2O5–Si/Nb–Si (Si doping less than 5 at. %) capacitor structures is hypothesized in order to explain the I–V and C–V characteristics.