STUDIES ON STRUCTURAL, SURFACE MORPHOLOGICAL, OPTICAL, LUMINESCENCE AND UV PHOTODETECTION PROPERTIES OF SOL–GEL Mg-DOPED ZnO THIN FILMS
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Date
2018-03
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Université de M'sila
Abstract
Undoped and magnesium-doped zinc oxide thin ¯lms were prepared by the sol–gel method. Results
from X-ray di®raction indicated that the ¯lms exhibited a hexagonal wurtzite structure and were
highly oriented along the c-axis. The intensity of the (002) di®raction peak increased with increasing
the Mg doping concentration. Also, Mg doping inhibited the growth of crystallite size which decreased
from 46nm to 38nm with doping concentration. Morphological studies by atomic force
microscopy (AFM) indicated the uniform thin ¯lm growth and the decreasing of grain size and
surface roughness with Mg doping. Optical analysis showed that the average transmittance of all
¯lms was above 90% in the visible range and Mg doping has signi¯cantly enhanced the bandgap
energy of ZnO. Two Raman modes assigned to E2L and E2H for the ZnO wurtzite structure were
observed for all ¯lms. UV emission peak and three defect emission peaks in the visible region were
observed by photoluminescence measurements at room temperature. The intensity ratio of UV
emission to the visible emission increased with the Mg concentration. Photocurrent measurements
revealed that all ¯lms presented the photoresponses with n-type semiconducting behavior and their
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generated photocurrents were reduced by Mg doping. The prepared thin ¯lms of high quality with improved properties by Mg doping could be proposed to workers in the ¯eld of optoelectronic devices for using them as a strong candidate.