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Influence of Mg doping on the morphology and optical properties of ZnO films for enhanced H 2 sensing
Author(s) -
Vijayalakshmi K.,
Karthick K.
Publication year - 2013
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.22274
Subject(s) - materials science , photoluminescence , crystallinity , doping , thin film , band gap , analytical chemistry (journal) , surface roughness , grain size , microstructure , absorption (acoustics) , ultraviolet , transmittance , sputtering , optoelectronics , nanotechnology , composite material , chemistry , chromatography
Highly oriented ZnO and Mg doped ZnO thin films were fabricated on Al 2 O 3 substrate by sputtering at room temperature. The effect of Mg doping on the structural, optical, and morphological properties of ZnO film was investigated. The intensity of (002) peak in X‐ray diffraction measurements revealed the influence of Mg doping on the crystallinity and orientation of ZnO film. Photoluminescence (PL) results show that the Ultraviolet (UV) emission peak was shifted to lower wavelength side for Mg:ZnO film indicating the possibility for quantum confinement. UV–vis–NIR optical absorption revealed an improvement in optical transmittance from 70 to 85%, and corresponding optical band gap from 3.25 to 3.54 eV. Atomic force microscope (AFM) images revealed the nano‐size particulate microstructure of the films. The surface topography of Mg doped ZnO film confirmed decreased grain size with large surface roughness and increased surface area, favorable for sensing. Pure ZnO and Mg doped ZnO film were used as active layer and tested for its sensing performance to hydrogen. Compared to undoped ZnO, 22 at.% Mg doped ZnO film showed much higher sensor response to H 2 at a concentration as low as 200 ppm and at a lower operating temperature of 180°C. A linear sensor response was observed for H 2 concentration in the range of 100–500 ppm. Microsc. Res. Tech. 76:1118–1124, 2013 . © 2013 Wiley Periodicals, Inc.