Influence of deposition conditions on structural, electrical, and optical properties of cadmium oxide thin films deposit
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Influence of deposition conditions on structural, electrical, and optical properties of cadmium oxide thin films deposited using the spray pyrolysis technique M. R. Sayas1 and M. R. Fadavieslam1,* 1
School of Physics, Damghan University, Damghan, Iran
Received: 2 July 2020
ABSTRACT
Accepted: 17 August 2020
In this study, thin films of cadmium oxide (CdO) were deposited on soda-lime glass substrates using the simple spray pyrolysis technique using a cadmium acetate precursor. The results regarding the structural, electrical, and optical properties of the layers as a function of the substrate temperature ranging from 280 to 340 °C, spray rate ranging from 5 to 20 ml/min, and volume of solution ranging from 50 to 125 ml were systematically studied. The X-ray diffraction (XRD) analysis revealed that all the thin films had a polycrystalline nature with the fcc structure of single-phase CdO. The analysis also showed peaks related to (111), (200), (220), and (311) planes. The field emission scanning electron microscopy (FE-SEM) images showed that the morphology surface of the thin films was spherical. The atomic force microscopy (AFM) analysis demonstrated that the roughness of thin films ranged from 21.16 to 60.9 nm. The Hall effect and thermoelectric studies revealed that the films exhibited an n-type conductivity. The Hall effect measurement study also showed that the carrier concentration (n) and carrier mobility were of the order of 1019 cm- 3 and 10- 2 cm- 2/ v s, respectively. The obtained values for the optical bandgap ranged from 2.29 to 2.56 eV, where the amount of the optical bandgap for the thin films decreased as the substrate temperature increased.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Transparent conducting oxide (TCO) materials such as zinc oxide (ZnO) [1], copper oxide (CuO) [2], tin oxide (SnO2) [3], indium oxide (In2O3) [4], and cadmium oxide (CdO) [5] have a special place in the thin film technology thanks to their highly visible transparency and high electrical conductivity [6]. A wide
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https://doi.org/10.1007/s10854-020-04275-w
range of applications in electronics and optoelectronics would be absent now without these features. Cadmium oxide (CdO) belongs to the family of transparent conducting oxide films. It is a degenerate n-type semiconductor given the presence of interstitial Cd atoms and oxygen vacancies, both of which act as donors [7, 8]. Also, it has a narrow bandgap of * 2.4 eV and a face-centered cubic crystal structure
J Mater Sci: Mater Electron
[9–11]. These properties render CdO useful for technological and industrial applications, especially in the field of optoelectronic devices such as solar cells [12], phototransistors [13], transparent electrodes [14], solid-state gas sensors [15], photo-detectors [10], optical communication [16], IR heat mirrors [17], flat panel displays [18], smart windows [19], IR detectors [20], liquid crystal displays [21], photodiodes [22], a
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