Low Frequency Noise of Nb2O5 Thin Insulating Films

Low Frequency Noise of Nb2O5 Thin Insulating Films

Paper in proceedings (conference paper)

A low frequency noise and charge carriers transport mechanism analysis have been performed on Nb – Nb2 O5 structures of various thickness to determine the mechanism of current flow and current noise sources. At low applied voltage and room temperature the charge carrier flow give thermally excited electrons hopping from one isolated state to the next. This mechanism yields an ohmic characteristic, exponentially dependent on temperature. At high fields and room temperature the rate limiting steps in the current flow is field-enhanced thermal excitation of trapped electrons into the conduction band. This process is known as Poole-Frenkel effect. In this case the barriers on electrodes determine the current value. Noise spectral density in low frequency range may be considered as superposition of 1/fa noise, burst noise, shot noise and thermal noise. Fluctuation of polarisation and fluctuation of mechanical strain may cause another kind of noise, which may be of importance. Last is the contact resistance noise component, which also makes some structures to be noisy. Two kinds of burst noise can be distinguished: Partial discharges in high electric field and regenerative micro-breaks cause two state RTS like noise, whereas charge transport and polarisation fluctuation bring about a multi-state continuous spectrum noise.

A low frequency noise and charge carriers transport mechanism analysis have been performed on Nb – Nb2 O5 structures of various thickness to determine the mechanism of current flow and current noise sources. At low applied voltage and room temperature the charge carrier flow give thermally excited electrons hopping from one isolated state to the next. This mechanism yields an ohmic characteristic, exponentially dependent on temperature. At high fields and room temperature the rate limiting steps in the current flow is field-enhanced thermal excitation of trapped electrons into the conduction band. This process is known as Poole-Frenkel effect. In this case the barriers on electrodes determine the current value. Noise spectral density in low frequency range may be considered as superposition of 1/fa noise, burst noise, shot noise and thermal noise. Fluctuation of polarisation and fluctuation of mechanical strain may cause another kind of noise, which may be of importance. Last is the contact resistance noise component, which also makes some structures to be noisy. Two kinds of burst noise can be distinguished: Partial discharges in high electric field and regenerative micro-breaks cause two state RTS like noise, whereas charge transport and polarisation fluctuation bring about a multi-state continuous spectrum noise.

Noise,Fluctuations, Niobium oxide, Thin film

SEDLÁKOVÁ, V., DOBIS, P., ŠIKULA, J., HOSCHL, P., SITA, Z., ZEDNÍČEK, T.

01.01.2003

CNRL s.r.o.

Czech Republic

80-239-1005-1

Proceedings of the 17th International Nonference Noise and Fluctuations ICNF 2003

141

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