Fabrication Process Of p-Type Zno Thin Film By Rf Sputtering Technique

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Date
2015-07
Authors
Abdulrazzaq, Afef Ismail
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Publisher
Universiti Sains Malaysia
Abstract
High purity targets of ZnO (99.99%) and AlN (99.999%) were used in the sputtering process to prepare (Al-N) codoped ZnO thin films using RF sputtering technique. The effect of preparation conditions on the structural, optical and the electrical properties of the prepared films were investigated. X-ray diffraction (XRD), AFM, FESEM, ultraviolet and visible (UV-V) transmission spectrometer, PL and Raman spectroscopy were employed for sample characterization. The Hall Effect technique was used for the measurement of resistivity, carrier concentration, Hall mobility and the conduction type of the produced films. When only argon (Ar) used as working gas, no nitrogen detected in the codoped ZnO film. No nitrogen detected in these samples even after annealing in nitrogen ambient at different temperatures. However, by introducing nitrogen (N2) and argon (Ar) as working gases at the ratio of (80:20), nitrogen was detected in the prepared samples.The X-ray diffraction revealed the preferred (002) phase c-axis orientation of the deposited films while the UV-V spectra analysis yielded the energy band gap of the films in the range of (3.24 – 3.52) eV. Raman spectra and EDX analysis proved the presence of nitrogen in the film that could have been incorporated during the fabrication process. The observed peak at 276 cm-1 of Raman spectra was attributed to nitrogen while the peak at 578.58 cm-1 was attributed to A1 (LO) mode of the AlN doped ZnO films. The films with p-type conductivity (0.01 Ω-1cm-1–1.91 Ω-1cm-1) have been achieved at the fabrication conditions of 80 (N2): 20 (Ar) gas ratio, (175-225) W RF power of ZnO target and (90-100) W RF power of AlN target. The mechanism for the p-type conductivity was suggested to be attributed to the formation of NO acceptor and N-Al-N complex acceptor states at the shallow energy levels in the energy band gap of the ZnO. With the optimum fabrication conditions, the highest carrier concentration of 3.68 × 1021 cm-3 for one sample and the highest carrier mobility of 117 cm2V-1s-1 for the other sample of p-type ZnO have been achieved in the present work, which subsequently shown to have formed good p-n junction device.
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Keywords
To prepare codoped ZnO thin films , using RF sputtering technique.
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