A defect state was found, after post-deposition annealing in O, by using a novel zero-bias thermally stimulated current spectroscopic technique. The activation energy was estimated to be about 0.3eV. The available evidence suggested that the defect was a hole trap, and an acceptor level, which was due to the substitution of Si for Ta. The presence of Si contamination, due to the diffusion of Si from a Si substrate, was confirmed by secondary-ion mass spectrometric results.

W.S.Lau, K.K.Khaw, P.W.Qian, N.P.Sandler, P.K.Chu: Journal of Applied Physics, 1996, 79[11], 8841-3