Monochromatic photoluminescence obtained from embedded ZnO nanodots in an ultrahard diamond-like carbon matrix

• Published in: Diamond and related materials Vol. 17; no. 2; pp. 167 - 170
• Main Authors: Hsieh, J., Chua, Daniel H.C., Tay, B.K., Teo, E.H.T., Tanemura, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2008; Elsevier
• Subjects: Cathodic arc discharge; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Diamond-like carbon; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of nanoscale materials; Nanocontacts; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties characterization; Photoluminescence; Physics; Specific materials; Nanoparticles; Diamond-like carbon; Cathodic arc discharge; Optical properties characterization; Defect states; Nanocluster; Electronic properties; Amorphous thin film; Photoluminescence; Mechanical properties; Thin films; Young modulus; Self-assembly; Energy gap; Electronic structure; Light emission; Transmission electron microscopy; Optical properties; Zinc oxide; Nanodot; Nanostructured materials; Vacuum deposition; Absorption edge; X-ray photoelectron spectra
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2007.11.015

At room temperature, we observe the self assembly of nanoclusters in an amorphous matrix using a vacuum deposition technique. Self-assembled ZnO nanoclusters embedded in hard diamond-like amorphous carbon thin films, deposited by high vacuum Filtered Cathodic Vacuum Arc (FCVA) technique at room temperature without post-processing, have been observed. A selective self assembly of metal and oxygen ions in a 3-element plasma was observed. XPS distinctly showed presence of ZnO and DLC-mixture in 5, 7 and 10 at.% Zn (in target) films while maintaining high sp 3 content. This in turn improved the Young's modulus value of the ZnO nanoclusters embedded in DLC film (~ 220 GPa) compared to bulk ZnO (~ 110 GPa). Films with ZnO detected were observed to exhibit absorption edge at 377 nm monochromatic UV light emissions. This corresponded to a band gap value of about 3.30 eV. The emission with greatest intensity (after normalization) was detected from 10 at.% Zn (in target) film where presence of ZnO nanoclusters (~ 40 nm) in DLC matrix were confirmed by TEM. This showed that well-defined crystalline ZnO nanoclusters contributed to strong PL signal. Strong monochromatic emissions detected hinted that no defect states were present.