Publication Type:Journal Article
Source:Applied Physics Letters, Volume 99, Number 11 (2011)
Keywords:Bi-layer, Capacitance, Capacitance enhancement, Classical limits, Experimental evidence, Ferroelectric materials, ferroelectricity, Gate oxide, Heterojunctions, lead, Mean field theory, Nano scale, Nanocomposite films, NanoScale Transistors, nanostructured materials, Nanotechnology, negative capacitance, Negative capacitance effect, Proof of concept, SrTiO, Strontium alloys, Strontium titanates, Subthreshold slope, Tuning parameter, zirconium
We report a proof-of-concept demonstration of negative capacitance effect in a nanoscale ferroelectric-dielectric heterostructure. In a bilayer of ferroelectric Pb(Zr0.2Ti0.8)O3 and dielectric SrTiO3, the composite capacitance was observed to be larger than the constituent SrTiO3 capacitance, indicating an effective negative capacitance of the constituent Pb(Zr0.2Ti0.8)O3 layer. Temperature is shown to be an effective tuning parameter for the ferroelectric negative capacitance and the degree of capacitance enhancement in the heterostructure. Landau's mean field theory based calculations show qualitative agreement with observed effects. This work underpins the possibility that by replacing gate oxides by ferroelectrics in nanoscale transistors, the sub threshold slope can be lowered below the classical limit (60 mV/decade). © 2011 American Institute of Physics.
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