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SUMMARY:Sputter-deposited ZnO and reactivity of ZnO/Ti interfaces
DTSTART:20151207T131500
DTEND:20151207T141500
DTSTAMP:20260916T202714Z
UID:1de26a0c0c92e57774ee930f1ac549ea91e9edff461f8d21f76b9f11
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Sergey Grachev\, Laboratoire Surfaces du Verre et Interfac
 es (SVI)\, Saint-Gobain France\nSaint-Gobain has been producing glass for 
 350 years. Application of transparent multilayers on glass is the principl
 e way to alter and add properties to glass: conductive\, optical\, mechani
 cal and others. Magnetron sputtering for film’s deposition is the method
  of choice in industry due to its high deposition rates\, homogeneity of t
 he deposit\, and its flexibility to adjust to a very wide range of materia
 ls. One of the important products of Saint-Gobain is low-emissive window g
 lass\, based on Ag films for thermal isolation of buildings by effective r
 eflecting the IR radiation. Such low-e stacks are composed of an ultrathin
  film of Ag\, a ZnO layer used as a substrate for silver growth and\, in s
 ome cases\, a few nm of Ti in between as adhesion enhancer.\nZnO is a piez
 oelectric semiconductor composed of alternating planes of Zn2+ and O2– i
 n the c-direction of the lattice. Thus the (0001) surface can be Zn- or O-
 terminated. These two surfaces have in fact rather different properties. T
 he two surfaces can be identified by a feature in the band structure attai
 ned with X-ray photoelectron spectroscopy (XPS). We managed to control the
  orientation of the sputter-deposited ZnO films by applying a potential to
  the substrate during deposition. It appeared that the preferential orient
 ation can be managed only in a narrow range of temperatures.\nIn contact w
 ith Ti\, ZnO films\, nominally\, form an Ohmic contact. However\, the chem
 ical reactivity can play an important role at such interfaces. We have stu
 died ZnO/Ti interfaces by high energy XPS (HAXPES) at Bessy II synchrotron
 . This technique\, contrary to conventional XPS\, allows for photoelectron
  detection from buried (down to 30 nm) interfaces due to their longer mean
  free path. We managed to follow the chemical reaction in ZnO/Ti films dur
 ing annealing. It results in oxidation of Ti\, appearance of metallic Zn a
 nd its diffusion to the surface and consequent evaporation. We showed that
  deposition conditions of ZnO impact its stability in such chemical reacti
 on.\nBio: Sergey Grachev\n1990 – 1996: Department of Solid State Physics
 \, Faculty of Experimental and Theoretical Physics at Moscow Engineering P
 hysics Institute (State University).\n1996 – 1998: PhDstudent at the Ins
 titute for Nuclear Research (Moscow)\, Russian Academy of Sciences\, “Ef
 fect of oxygen doping in YBaCuO studied by inelastic magnetic neutron scat
 tering” (not finished)\n1998 – 2003: PhDstudent at University of Groni
 ngen. PhD thesis: “Manipulation and control of growth of magnetic iron n
 itride films”.\n2003 – 2006:  PostDoc researcher at the Netherlands I
 nstitute for Metals Research (Delft)\, “Microstructure of- and stress in
 - PVD Cr coatings”.\n2006 – current Surface du verre et interfaces\, C
 NRS/Saint-Gobain\, Saint-Gobain Recherche\, Aubervilliers\, France
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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