The role of Al, Ba, and Cd dopant elements in tailoring the properties of c-axis oriented ZnO thin films

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• 关键词：ZnO ; Sol-gel ; XRD ; Crystallite size ; c-axis ; Band gap energy ; Debye-Waller factor
• 刊名：Physica B: Condensed Matter
• 出版年：2017
• 出版时间：1 February 2017
• 年：2017
• 卷：506
• 期：Complete
• 页码：83-93
• 全文大小：2533 K
• 卷排序：506

文摘

Highly c-axis oriented un-doped ZnO and Al-, Ba-, and Cd-doped ZnO thin films were successfully deposited on glass substrate employing sol-gel spin coating method. XRD analysis showed that all thin films possess hexagonal wurtzite structure with preferred orientation along c-axis. Field emission scanning electron microscope (FESEM) was used to study the morphology of thin films. The morphology consists of spherical and non-spherical shape grains. EDX analysis confirms the presence of O, Zn, Al, Ba, and Cd in the relevant thin films. The optical properties of thin films were studied using UV–Vis spectrometer. All thin films possess more than 85% optical transmittance in the visible region. Blue shift in optical band gap Eg has been observed on doping with Al, whereas doping with Ba and Cd resulted in red shift of Eg. Urbach energy Eu of all doped ZnO thin films was found to have excellent correlation with their band gap energy Eg. Moreover, Eg increases while Eu decreases on the increase in crystallite size D. Optical parameters Eg and Eu as well as structural parameters lattice strain and stacking fault probability also show excellent correlation with the B-factor or the mean-square amplitude of atomic vibrations <u2> of the dopant elements. Electrical conductivity measurement of the thin films was carried out using two-point probe method. The electrical conductivity was found to increase with the increase in crystallite orientation along c-axis.