Differences between direct current and alternating current capacitance nonlinearities in high-k dielectrics and their relation to hopping conduction

Capacitance nonlinearities were studied in atomic layer deposited HfO2 films using two types of signals: a pure ac voltage of large magnitude (ac nonlinearities) and a small ac voltage superimposed to a large dc voltage (dc nonlinearities). In theory, ac and dc nonlinearities should be of the same o...

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Bibliographic Details
Published in:Journal of applied physics 2014-08, Vol.116 (8)
Main Authors: Khaldi, O., Gonon, P., Vallée, C., Mannequin, C., Kassmi, M., Sylvestre, A., Jomni, F.
Format: Article
Language:English
Subjects:
ALTERNATING CURRENT
Applied physics
CAPACITANCE
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
DEPOSITION
DIELECTRIC MATERIALS
DIRECT CURRENT
ELECTRIC POTENTIAL
Electrode polarization
ELECTRODES
Hafnium oxide
HAFNIUM OXIDES
Hopping conduction
IMPEDANCE
LAYERS
NONLINEAR PROBLEMS
Percolation
Physics
POLARIZATION
SIGNALS
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Summary:Capacitance nonlinearities were studied in atomic layer deposited HfO2 films using two types of signals: a pure ac voltage of large magnitude (ac nonlinearities) and a small ac voltage superimposed to a large dc voltage (dc nonlinearities). In theory, ac and dc nonlinearities should be of the same order of magnitude. However, in practice, ac nonlinearities are found to be an order of magnitude higher than dc nonlinearities. Besides capacitance nonlinearities, hopping conduction is studied using low-frequency impedance measurements and is discussed through the correlated barrier hopping model. The link between hopping and nonlinearity is established. The ac nonlinearities are ascribed to the polarization of isolated defect pairs, while dc nonlinearities are attributed to electrode polarization which originates from defect percolation paths. Both the ac and dc capacitance nonlinearities display an exponential variation with voltage, which results from field-induced lowering of the hopping barrier energy.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4893583