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

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/1.4914522· OSTI ID:1229041
 [1];  [2];  [3];  [1];  [3];  [4]
  1. Hacettepe Univ., Ankara (Turkey)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Bilkent Univ., Ankara (Turkey)
  4. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
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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. Here, 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.

Research Organization:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC00112704; AC02-98CH10886
OSTI ID:
1229041
Alternate ID(s):
OSTI ID: 1228236
Report Number(s):
BNL-111116-2015-JA; JAPIAU
Journal Information:
Journal of Applied Physics, Vol. 117, Issue 10; ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

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74 ATOMIC AND MOLECULAR PHYSICS
X-ray diffraction
Electronic bandstructure
Nanocrystals
Atomic properties
Semiconductor device fabrication
X-ray photoelectron spectroscopy
Scanning electron microscopy
Nanoclusters
Thin films
Extended X-ray absorption fine structure