Effect of Mg and Cu doping on structural, optical, electronic, and thermal properties of ZnS quantum dots
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Effect of Mg and Cu doping on structural, optical, electronic, and thermal properties of ZnS quantum dots Zein K. Heiba1,4,*, Mohamed Bakr Mohamed2,4,*
, A. M. El-naggar3,4, and A. A. Albassam3,5
1
X-ray Diffraction and Crystal Structural Unit, Faculty of Science, Ain Shams University, Cairo, Egypt Physics Department, Faculty of Science, Taibah University, Al-Madinah Al-Munawara, Saudi Arabia 3 Physics & Astronomy Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia 4 Physics Department, Faculty of Science, Ain Shams University, Cairo, Egypt 5 K.A.CARE Energy Research and Innovation Center at Riyadh, Riyadh, Saudi Arabia 2
Received: 23 July 2020
ABSTRACT
Accepted: 9 October 2020
Undoped and 10% Mg or Cu-doped ZnS quantum dots (Zn0.9Mg0.1S and Zn0.9Cu0.1S) were prepared by a simple chemical method at low temperature (300 °C). The effect of doping on structural characteristics was investigated using Rietveld profile method and the high-resolution transmission electron microscope techniques. Differential scanning calorimetry (DSC) scans were recorded in the temperature range 23–600 °C with different heating rates (5 to 30 °C/min). The model-free isoconversional method was applied to explore the effect of doping on the reaction and the growth mechanism of nano-ZnS. Diffuse UV reflectance revealed an increase of the optical energy gap upon doping with Mg, while it decreased as ZnS was doped with Cu. The change in energy gap upon doping was explained using density function theory calculation. The photoluminescence (PL) spectra revealed violet, blue, green colors depended on the composition and excitation wavelength used in the study. The intensity of PL has been increased for doped samples compared with pristine ZnS. Tuning the energy gap of ZnS through doping enable applications for light-harvesting and photocatalytic degradation in the visible region.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Recently, II–VI semiconductors materials attracted a large technological interest because of its wide bandgap nature and their potential optoelectronic applications [1]. The distinctive characteristics of semiconductor nanoparticles have attracted also the
researcher in the past few decades [2] as compared with the bulk one, due to their new electrical and optical characteristics [3]. Among them, the zinc chalcogenides (ZnS) are extensively investigated for several uses in blue laser and visible light emittingdevices, optical computing [4] and bioimaging applications [5]. ZnS has a bandgap energy of 3.72
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https://doi.org/10.1007/s10854-020-04647-2
J Mater Sci: Mater Electron
and 3.77 eV for cubic sphalerite and hexagonal wurtzite phases, respectively [6]. The cubic ZnS only is stable at room temperature, and it can transform into the hexagonal phases at high temperatures [6]. The structure, optical, and magnetic properties of semiconductors chalcogenides can be
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