A Study on Structural and Optical Properties of Nanostructure MgxZn1-xO Thin Films Using Pulsed Laser Deposition
Engineering and Technology Journal,
2014, Volume 32, Issue 6, Pages 1030-1050
AbstractFor this paper, films have been grown under various deposition conditions in order to understand the effect of processing on the film properties and to specify the optimum condition, namely substrate at temperatures of 400°C, oxygen pressure (2×10-1) mbar, laser fluence 400 mJ, and with different Mg doping (x=0, 0.02, 0.04, 0.06), using double frequency Q-switching Nd:YAG laser beam (wavelength 532nm), repetition rate (1-6) Hz and the pulse duration of (10 ns), to deposit MgxZn1-xO films on glass substrates with thickness of about 200±10 nm for all MgxZn1-xO films at different deposition condition and the number of laser pulses was 100 pulses. The X-rays spectra revealed that the presence of diffraction peaks indicates that the polycrystalline of the films depended strongly on the Mg-content in the layers. All the grown films is (101) as predominant reflection. The Scanning Electron Microscopy (SEM) images, the average grain size less than 50 nm. From the study of atomic force microscopy (AFM), we can determine the root mean square (RMS) surface roughness of Mg doped ZnO films. The optical properties were characterized by the transmittance and absorption spectroscopy at room temperature, measured in the range from (300 - 900) nm. For all the films, the average transmittance in the visible wavelength region λ = (400 - 800) nm is greater than (70%). The maximum value of the transmittance is greater than (95%) was obtained for these films. (Eg) values of MgxZn1-xO thin films are (3.37, 3.59, 3.82, and 4)eV corresponding to the Mg-content (x = 0, 0.02, 0.04 and 0.06) respectively. In other word, the optical band gap of MgxZn1-xO thin films become wider as Mg-content increases and can be precisely controlled between 3.37 and 4eV.
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