Effect of Ar/O2 gas ratios on the structure, electrical and optical properties of Na-doped ZnCdO film synthesized by magnetron sputtering
Na-doped ZnCdO films [ZCO:Na] were grown on quartz substrates at different ratios of argon to oxygen gas flow (Ar:O2) by the radio frequency magnetron sputtering method. The influence of Ar:O2 ratio on structure, electrical and optical properties was investigated by using X-ray diffraction, X-ray photoelectron spectroscopy, Transmission electron microscopy, Hall measurements (Hall), optical absorption spectra and Photoluminescence. Results indicated that all obtained ZCO:Na thin films possess the hexagonal wurtzite structure and free from the formation of secondary phases. As the Ar:O2 ratios change from 1:5 to 5:1, at first the Eg increases with the Ar:O2 ratios increasing and reaches a maximum value at the Ar:O2 ratio of 1:1, then decreases evidently with the Ar:O2 ratios increasing continually. It is found that the lower Ar:O2 ratio is propitious to obtain n-type ZCO:Na film, while the relative higher Ar:O2 ratio is required to obtain p-type ZCO:Na thin films. When the Ar:O2 ratio is 1:1, the ZCO:Na film shows the best p-type conduction characteristics, which has a hole concentration of 1.13 × 1016 cm−3, Hall mobility of 2.54 cm2 V−1 s−1 and resistivity of 2.53 × 102 Ω cm. In addition, the mechanism of the influence of Ar:O2 ratio on the electrical and optical properties of the film as well as the mechanism of p-type conductivity was discussed in this work.
KeywordsMagnetron Sputtering Radio Frequency Magnetron Sputtering NaZn ICDD Card Radio Frequency Reactive Magnetron
The authors would like to thank financial support of the National Natural Science Foundation of China under Grant Nos. 11254001, 61505067, 61475063, 11204104, the Program for the Development of Science and Technology of Jilin Province Grant No. 20150520086JH, the Program for New Century Excellent Talents in University Grant No. NCET-13-0824.
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