The effects of nitrogen doping as a terminator in an anodically oxidized film of tantalum have been investigated.
In the oxide film of nitrogen-free tantalum, the electric leakage current abruptly increased with the applied voltage. It is well-known as the Poole-Frenkel effect  . After annealing at 623K in a hydrogen atmosphere, the leakage current increased.
On the other hand, in the oxidized films of nitrogen-doped tantalum the leakage current increased in proportion to the applied voltage, but it was very small as compared with the nitrogen-free oxide. Moreover the leakage current decreased after annealing. The decrement strongly depended on the amount of doped nitrogen.