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Structure and effects of annealing in colloidal matrix-free Ge quantum dots

DOI: 10.1107/S1600577514022486 DOI Help
PMID: 25537595 PMID Help

Authors: Yuanpeng Zhang (Queen Mary, University of London) , Ali Karatutlu (Queen Mary, University of London) , Osman Ersoy (Queen Mary, University of London) , William Little (Queen Mary, University of London) , Giannantonio Cibin (Diamond Light Source) , Andrew Dent (Diamond Light Source Ltd) , Andrei Sapelkin (Queen Mary University of London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Synchrotron Radiation , VOL 22 , PAGES 105 - 112

State: Published (Approved)
Published: January 2015
Diamond Proposal Number(s): 8257 , 8707

Abstract: The structure of small (2–5 nm) Ge quantum dots prepared by the colloidal synthesis route is examined. Samples were synthesized using either GeO2 or GeCl4 as precursor. As-prepared samples were further annealed under Ar or H2/Ar atmosphere at different temperatures in order to understand the effect of annealing on their structure. It was found that as-prepared samples possess distinctly different structures depending on their synthesis route as indicated by their long-range ordering. An appreciable amount of oxygen was found to be bound to Ge in samples prepared with GeO2 as a precursor; however, not for GeCl4. Based on combined transmission electron microscope, Raman, X-ray diffraction and X-ray absorption measurements, it is suggested that as-prepared samples are best described by the core-shell model with a small nano-crystalline core and an amorphous outer layer terminated either with oxygen or hydrogen depending on the synthesis route. Annealing in an H2Ar atmosphere leads to sample crystallization and further nanoparticle growth, while at the same time reducing the Ge—O bonding. X-ray diffraction measurements for as-prepared and annealed samples indicate that diamond-type and metastable phases are present.

Journal Keywords: Ge Quantum Dots (Qds); Annealing; Matrix-Free; Combined Characterization; Core-Shell Model.

Subject Areas: Physics, Chemistry, Biology and Bio-materials


Instruments: B18-Core EXAFS

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