Low-temperature synthesis and characterization of ZnO quantum dots

Abstract ZnO quantum dots (QDs) were fabricated at low temperature of 200 °C through thermal decomposition method with slight introduction of sodium dodecyl sulfate (SDS). The morphology, structure and optical properties were investigated by the methods of X-ray diffraction (XRD), transmission electron microscope (TEM), photoluminescence (PL) and Raman spectrum, respectively. The XRD results showed the as-synthesized ZnO QDs had hexagonal wurtzite structure and the average grain size estimated from Scherrer formula was 7.5 nm which had a good agreement with TEM result. And it is evident that the introduction of SDS can actually decrease the grain size to form ZnO QDs. The Raman results also indicated that the ZnO QDs keep the overall crystal structure of the bulk ZnO. Both spatial confinement within the dot boundaries and phonon localization by defects were the mainly reason for the only few cm−1 redshift of the Raman scatter peaks. The room-temperature photoluminescence reveals that the as-prepared ZnO QDs exhibit an ultraviolet emission at 380 nm and a broad deep level emission band in the range of 420–700 nm in wavelength, which testified the Raman and XRD results that the as-synthesized ZnO QDs had defects. Moreover, the growth mechanism of ZnO QDs was also discussed in the article.

[1]  Lin Guo,et al.  Highly monodisperse polymer-capped ZnO nanoparticles: Preparation and optical properties , 2000 .

[2]  Zhong Lin Wang.  Zinc oxide nanostructures: growth, properties and applications , 2004 .

[3]  A. Balandin,et al.  Origin of ultraviolet photoluminescence in ZnO quantum dots: Confined excitons versus surface-bound impurity exciton complexes , 2004 .

[4]  H. Koinuma,et al.  Room-temperature luminescence of excitons in ZnO/(Mg, Zn)O multiple quantum wells on lattice-matched substrates , 2000 .

[5]  Bixia Lin,et al.  Green luminescent center in undoped zinc oxide films deposited on silicon substrates , 2001 .

[6]  Sang‐Woo Kim,et al.  Artificial control of ZnO nanodots by ion-beam nanopatterning , 2005 .

[7]  Bruce E. Gnade,et al.  Mechanisms behind green photoluminescence in ZnO phosphor powders , 1996 .

[8]  D. Lucca,et al.  Synthesis of ZnO nanocrystals by subsequent implantation of Zn and O species , 2005 .

[9]  T. Seong,et al.  Fabrication of ZnO quantum dots embedded in an amorphous oxide layer , 2004 .

[10]  A. Meijerink,et al.  The influence of particle size on the luminescence quantum efficiency of nanocrystalline ZnO particles , 2001 .

[11]  C. Xie,et al.  Investigation of gas sensitivity of Sb-doped ZnO nanoparticles , 2005 .

[12]  Zhongfan Liu,et al.  Low-temperature growth and properties of ZnO nanowires , 2004 .

[13]  M. Rajalakshmi,et al.  Optical phonon confinement in zinc oxide nanoparticles , 2000 .

[14]  Zhong Lin Wang,et al.  Nanobelts of Semiconducting Oxides , 2001, Science.

[15]  Wai Kin Chan,et al.  Different origins of visible luminescence in ZnO nanostructures fabricated by the chemical and evaporation methods , 2004 .

[16]  Ningsheng Xu,et al.  Dissolving Behavior and Stability of ZnO Wires in Biofluids: A Study on Biodegradability and Biocompatibility of ZnO Nanostructures , 2006 .

[17]  A. Balandin,et al.  Origin of the optical phonon frequency shifts in ZnO quantum dots , 2005 .

[18]  Sang‐Woo Kim,et al.  Selective formation of ZnO nanodots on nanopatterned substrates by metalorganic chemical vapor deposition , 2003 .

[19]  L. Alexander,et al.  X-Ray diffraction procedures for polycrystalline and amorphous materials , 1974 .

[20]  W. Stark,et al.  Rapid synthesis of stable ZnO quantum dots , 2002 .

[21]  Alexander A. Balandin,et al.  Micro-Raman investigation of optical phonons in ZnO nanocrystals , 2005 .

[22]  A. M. Saitta,et al.  High-pressure Raman spectroscopy study of wurtzite ZnO , 2002 .

[23]  Dapeng Yu,et al.  Ultraviolet-emitting ZnO nanowires synthesized by a physical vapor deposition approach , 2001 .

[24]  Gang Xiong,et al.  Correlations among size, defects, and photoluminescence in ZnO nanoparticles , 2007 .

[25]  Myrtil L. Kahn,et al.  Experimental study of LO phonons and excitons in ZnO nanoparticles produced by room-temperature organometallic synthesis , 2006 .

[26]  Yu Hang Leung,et al.  Optical properties of ZnO nanostructures. , 2006, Small.

[27]  Yiying Wu,et al.  Room-Temperature Ultraviolet Nanowire Nanolasers , 2001, Science.

[28]  M. Zacharias,et al.  ZnO nanowires and nanobelts: Shape selection and thermodynamic modeling , 2007 .

[29]  R. Chang,et al.  Self-assembled 3D photonic crystals from ZnO colloidal spheres , 2003 .

[30]  Faqiang Xu,et al.  The electronic structure and spectral properties of ZnO and its defects , 2003 .