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Title: Effects of rapid thermal annealing on the structural and local atomic properties of ZnO: Ge nanocomposite thin films

We have investigated the structural and local atomic properties of Ge nanocrystals (Ge-ncs) embedded ZnO (ZnO: Ge) thin films. The films were deposited by sequential sputtering of ZnO and Ge thin film layers on z-cut quartz substrates followed by an ex-situ rapid thermal annealing (RTA) at 600 °C for 30, 60, and 90 s under forming gas atmosphere. Effects of RTA time on the evolution of Ge-ncs were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), hard x-ray photoelectron spectroscopy (HAXPES), and extended x-ray absorption fine structure (EXAFS). XRD patterns have clearly shown that fcc diamond phase Ge-ncs of sizes ranging between 18 and 27 nm are formed upon RTA and no Ge-oxide peak has been detected. However, cross-section SEM images have clearly revealed that after RTA process, Ge layers form varying size nanoclusters composed of Ge-ncs regions. EXAFS performed at the Ge K-edge to probe the local atomic structure of the Ge-ncs has revealed that as prepared ZnO:Ge possesses Ge-oxide but subsequent RTA leads to crystalline Ge structure without the oxide layer. In order to study the occupied electronic structure, HAXPES has been utilized. The peak separation between the Zn 2p and Ge 3d shows no significant change due to RTA.more » This implies little change in the valence band offset due to RTA.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [5]
  1. SNTG Laboratory, Department of Physics Engineering, Hacettepe University, 06800 Ankara (Turkey)
  2. National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  3. Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey)
  4. (Turkey)
  5. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
22399272
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION SPECTROSCOPY; ANNEALING; ELECTRONIC STRUCTURE; FCC LATTICES; FINE STRUCTURE; GERMANIUM; HARD X RADIATION; LAYERS; NANOCOMPOSITES; NANOSTRUCTURES; PHOTOELECTRON SPECTROSCOPY; QUARTZ; SCANNING ELECTRON MICROSCOPY; SPUTTERING; SUBSTRATES; THIN FILMS; VALENCE; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY; ZINC OXIDES