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

Journal Article · Sat Mar 14 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4914522· OSTI ID:22399272

Ceylan, Abdullah; Ozcan, Sadan ^[1]; Rumaiz, Abdul K. ^[2]; Caliskan, Deniz ^[3]; Ozbay, Ekmel ^[3]; Woicik, J. C. ^[4]

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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. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

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. This implies little change in the valence band offset due to RTA.

• OSTI ID: 22399272
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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