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| Titel: |
Understanding Thickness Effects in Thin Film Capacitors |
| Auteur: |
Lookman, A. Bowman, R. M. Gregg, J. M. Scott, J. F. Dawber, Matt Ruediger, A. |
| Verschenen in: |
Integrated ferroelectrics |
| Paginering: | Jaargang 61 (2004) nr. 1 pagina's 51-58 |
| Jaar: |
2004 |
| Inhoud: |
Pulsed Laser Deposition (PLD) was used to make Au/(Ba0.5Sr0.5)TiO3/(La0.5Sr0.5) CoO3/MgO thin film capacitor structures. Functional properties were studied with changing BST thickness from ∼1265 nm to ∼63 nm. The dielectric constant was found to decrease, and migration of Tm (the temperature at which the dielectric constant is maximum) to lower temperatures occurred as thickness was reduced. Curie-Weiss plots of the as-obtained dielectric data, indicated that the Curie temperature was also systemmatically progressively depressed. Further, fitting to expressions previously used to describe diffuse phase transitions suggested increased diffuseness in transformation behaviour as film thickness decreased. This paper discusses the care needed in interpreting the observations given above. We make particular distinction between the apparent Curie-temperature derived from Curie-Weiss plots of as-measured data, and the inherent Curie temperature determined after correction for the interfacial capacitance. We demonstrate that while the apparent Curie temperature decreases as thickness decreases, the inherent Curie temperature is thickness independent. Thickness-invariant phase transition behaviour is confirmed from analysis of polarisation loops, and from examination of the temperature dependence of the loss-tangent. We particularly note that correction of data for interfacial capacitance does not alter the position of Tm. We must therefore conclude that the position of Tm is not related simply to phase transformation behaviour in BST thin films. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 38 van 38 gevonden artikelen
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