advanced-nanotechnology-2019-accepted-abstracts

A p r i l 1 8 - 1 9 , 2 0 1 9

P a r i s , F r a n c e

Page 45

Nano Research & Applications

ISSN: 2471-9838

Advanced Nanotechnology 2019

EuroSciCon Conference on

Advanced Nanotechnology

n this paper, we conduct a first trial to study the dependence of photoluminescence (PL) emission, and optical absorption edge

of Zn

0.78

0.22

S quantum dots on thermally induced - poly to single crystalline structural phase transition and morphological

changes, along with excitation wavelength. It is found that, increasing annealing temperature (Ta) results in two structural

phase transitions: firstly, from polycrystalline cubic to crystalline hexagonal Zn

0.78

0.22

S structures at Ta 500

C, secondly,

from polycrystalline cubic to single crystalline predominant ZnO hexagonal structure at 600

C, accompanied by an increase

in XRD peaks intensity, sharpness, the crystallite size, the reduction of the internal local strain and the dislocation density, and

consequently red shift of the optical gap. In addition, analysis of HRTEM images and SAED patterns, FTIR and Raman spectra

indicates good agreement with XRD results. Moreover, the deconvoluted PL emission spectra at excitation wavelength 325 nm

of the as-prepared and annealed nanoparticles up to 500

C demonstrate UV- blue emission bands at 362, 395, 443, and 523 nm,

which quenched and red shifted to 402, 469, 509, 540 nm with increasing ex to 370 nm, along with the evolution of new emission

bands at 594, 637, and 685 nm. In addition, the as-synthesized Zn

0.78

0.22

S colloidal solution at ex of 325 nm reveals multiple

broad emission bands associated with quenching and red shift in the PL intensity with increasingex to 370 nm. Increasing Ta

up to 500 oC at ex of 370 nm results in quenching and red shift of the overall PL spectra, whereas at ex of 325 nm, no change

is observed. Moreover, Zn

0.78

0.22

S nanopowder at either 600 or 700 oC at ex 370 nm reveal new and red shifted PL emission

bands, along with a drastic increase in PL intensity by one order of magnitude higher than that observed at ex 325 nm. The

unusual excitation wavelength dependent enhancement and blue shift of PL in Zn

0.78

0.22

S nanopowder has demonstrated.

Trapping and recombination radiative levels have been identified and the corresponding energy band diagrams are suggested.

prof.m_osman@aun.edu.eg

Influence of Thermally Induced Poly to Single

Crystalline Structural Phase Transition on

Photoluminescence and Optical Absorption

behavior of Zn0.78Cd0.22S Quantum Dots for

Photo electronic applications

M. A. Osman, A. G. Abd-Elrahim

Physics Department, Faculty of Science, Assiut University

Nano Res Appl 2019, Volume:5

DOI: 10.21767/2471-9838-C2-034