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Title: Band bending at ferroelectric surfaces and interfaces investigated by x-ray photoelectron spectroscopy

This work reports on the use of X-ray photoelectron spectroscopy to quantify band bending at ferroelectric free surfaces and at their interfaces with metals. Surfaces exhibiting out-of-plane ferroelectric polarization are characterized by a band bending, due to the formation of a dipole layer at the surface, composed by the uncompensated polarization charges (due to ionic displacement) and to the depolarization charge sheet of opposite sign, composed by mobile charge carriers, which migrate near surface, owing to the depolarization electric field. To this surface band bending due to out-of-plane polarization states, metal-semiconductor Schottky barriers must be considered additionally when ferroelectrics are covered by metal layers. It is found that the net band bending is not always an algebraic sum of the two effects discussed above, since sometimes the metal is able to provide additional charge carriers, which are able to fully compensate the surface charge of the ferroelectric, up to the vanishing of the ferroelectric band bending. The two cases which will be discussed in more detail are Au and Cu deposited by molecular beam epitaxy on PbZr{sub 0.2}Ti{sub 0.8}O{sub 3}(001) single crystal thin layers, prepared by pulsed laser deposition. Gold forms unconnected nanoparticles, and their effect on the band bendingmore » is the apparition of a Schottky band bending additional to the band bending due to the out-of-plane polarization. Copper, starting with a given thickness, forms continuous metal layers connected to the ground of the system, and provide electrons in sufficient quantity to compensate the band bending due to the out-of-plane polarization.« less
Authors:
 [1]
  1. National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele-Ilfov (Romania)
Publication Date:
OSTI Identifier:
22390743
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1634; Journal Issue: 1; Conference: TIM-13 Physics Conference, Timisoara (Romania), 21-24 Nov 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHARGE CARRIERS; COPPER; DEPOLARIZATION; ELECTRIC FIELDS; ENERGY BEAM DEPOSITION; FERROELECTRIC MATERIALS; GOLD; INTERFACES; LASER RADIATION; LAYERS; LEAD COMPOUNDS; MOLECULAR BEAM EPITAXY; MONOCRYSTALS; NANOPARTICLES; POLARIZATION; SEMICONDUCTOR MATERIALS; THIN FILMS; TITANATES; X-RAY PHOTOELECTRON SPECTROSCOPY; ZIRCONIUM COMPOUNDS