Unravelling and controlling hidden imprint fields in ferroelectric capacitors
Liu, Fanmao (Institut de Ciència de Materials de Barcelona)
Fina, Ignasi (Institut Català de Nanociència i Nanotecnologia)
Bertacco, Riccardo (Politecnico di Milano)
Fontcuberta, Josep (Institut de Ciència de Materials de Barcelona)

Data:	2016
Resum:	Ferroelectric materials have a spontaneous polarization that can point along energetically equivalent, opposite directions. However, when ferroelectric layers are sandwiched between different metallic electrodes, asymmetric electrostatic boundary conditions may induce the appearance of an electric field (imprint field, E imp) that breaks the degeneracy of the polarization directions, favouring one of them. This has dramatic consequences on functionality of ferroelectric-based devices such as ferroelectric memories or photodetectors. Therefore, to cancel out the E imp, ferroelectric components are commonly built using symmetric contact configuration. Indeed, in this symmetric contact configuration, when measurements are done under time-varying electric fields of relatively low frequency, an archetypical symmetric single-step switching process is observed, indicating E imp ∼ 0. However, we report here on the discovery that when measurements are performed at high frequency, a well-defined double-step switching is observed, indicating the presence of E imp. We argue that this frequency dependence originates from short-living head-to-head or tail-to-tail ferroelectric capacitors in the device. We demonstrate that we can modulate E imp and the life-time of head-to-head or tail-to-tail polarization configurations by adjusting the polarization screening charges by suitable illumination. These findings are of relevance to understand the effects of internal electric fields on pivotal ferroelectric properties, such as memory retention and photoresponse.
Ajuts:	Ministerio de Economía y Competitividad MAT2014-56063-C2-1-R Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-734 Ministerio de Economía y Competitividad SEV-2015-0496
Nota:	Altres ajuts: 2011 BP-A_2 00014 d'AGAUR-Generalitat de Catalunya
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Ferroelectrics and multiferroics ; Information storage ; Photonic devices
Publicat a:	Scientific reports, Vol. 6 (April 2016) , art. 25028, ISSN 2045-2322

DOI: 10.1038/srep25028
PMID: 27122309

7 p, 654.3 KB

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