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

Abstract

The basic electrical properties of Nb 2 O 5 and Si-doped Nb 2 O 5 (Nb 2 O 5 –Si) thin films, which were obtained by anodically oxidizing Nb in an H 3 PO 4 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 Nb 2 O 5 and Nb 2 O 5 –Si (Si-doping less than 19 at. %). For the reverse bias condition, a Schottky-barrier is formed at the Au/Nb 2 O 5 and/or Au/Nb 2 O 5 –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 Nb 2 O 5 and/or Nb 2 O 5 –Si films. A schematic energy band diagram for Au/Nb 2 O 5 /Nb and/or Au/Nb 2 O 5 –Si/Nb–Si (Si doping less than 5 at. %) capacitor structures is hypothesized in order to explain the I – V and C – V characteristics.