Optoelectronic properties and doping of magnetron sputtered highly mismatched ZnO1-xTex alloy thin films

Liu, Chao Ping; Ho, Chun Yuen; Egbo, Kingsley O.; Li, Zhan Hua; Cong, Xiao; Yu, Kin Man

doi:10.1016/j.jallcom.2020.156950

Cited by 4 publications

(2 citation statements)

References 43 publications

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“…The optical properties of AZO thin films were investigated by SE. Unlike the traditional transmittance-reflectance measurements, SE can provide detailed optical properties including the dielectric function (ε = ε 1 + iε 2 , with ε 1 and ε 2 the real and imaginary parts respectively), the optical constants as well as the absorption coefficient (α) of thin films [40][41][42][43]. SE data analysis was based on the three-layer optical model, i.e.…”

Section: Resultsmentioning

confidence: 99%

Effects of oxygen flow ratio and thermal annealing on defect evolution of aluminum doped zinc oxide thin films by reactive DC magnetron sputtering

Liu

Egbo

et al. 2021

J. Phys.: Condens. Matter

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Al doped ZnO (AZO) is a promising transparent conducting oxide to replace the expensive Sn doped In2O3 (ITO). Understanding the formation and evolution of defects in AZO is essential for its further improvement. Here, we synthesize transparent conducting AZO thin films by reactive DC magnetron sputtering. The effects of oxygen flow ratio as well as the rapid thermal annealing (RTA) in different conditions on their structural and optoelectrical properties were investigated by a variety of analytical techniques. We find that AZO thin films grown in O-rich conditions exhibit inferior optoelectrical performance as compared with those grown in Zn-rich conditions, possibly due to the formation of excessive native acceptor defects and/or secondary phases (e.g. Al2O3). Temperature-dependent Hall measurements indicate that mobilities of these highly degenerate AZO films with N > 1020 cm−3 are primarily limited by ionized and neutral impurities, while films with relatively low N ∼ 1019 cm−3 exhibit a temperature-activated mobility owing to the grain-barrier scattering. As N increases, the optical band gap of AZO thin film increases as a result of Burstein–Moss shift and band gap narrowing. RTA treatments under appropriate conditions (i.e. at 500 °C for 60 s in Ar) can further improve the electrical properties of AZO thin film, with low resistivity of ∼6.2 × 10−4 Ω cm achieved, while RTA at high temperature with longer time can lead to the formation of substantial sub-gap defect states and thus lowers the electron mobility. X-ray photoelectron spectroscopy provides further evidence on the variation of Al (Zn) content at the surface of AZO thin films with different processing conditions.

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Section: Resultsmentioning

confidence: 99%

Effects of oxygen flow ratio and thermal annealing on defect evolution of aluminum doped zinc oxide thin films by reactive DC magnetron sputtering

Liu

Egbo

et al. 2021

J. Phys.: Condens. Matter

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“…In the field of Sputtering deposition techniques, RF magnetron sputtering is the most common [25,26], particularly with ZnTe as the unique target, to obtain ZnTeO alloys [27]. Recently, RF magnetron sputtering using two independent targets of ZnTe and ZnO was also used [28]. All these techniques were used indistinctly for both ZnO-based thin films and nanostructured compounds.…”

Section: Introductionmentioning

confidence: 99%

ZnOTe Compounds Grown by DC-Magnetron Co-Sputtering

Sánchez

Hernández‐Vélez

2021

Coatings

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ZnOTe compounds were grown by DC magnetron cosputtering from pure Tellurium (Te) and Zinc (Zn) cathodes in O2/Ar atmosphere. The applied power on the Zn target was constant equal to 100 W, while the one applied on the Te target took two values, i.e., 5 W and 10 W. Thus, two sample series were obtained in which the variable parameter was the distance from the Te targets to the substrate. Sample compositions were determined by Rutherford Backscattering Spectroscopy (RBS) experiments. Structural analysis was done using X-Ray diffraction (XRD) spectrometry and the growth of the hexagonal w-ZnO phase was identified in the XRD spectra. RBS results showed high bulk homogeneity of the samples forming ZnOTe alloys, with variable Te molar fraction (MF) ranging from 0.48–0.6% and from 1.9–3.1% for the sample series obtained at 5 W and 10 W, respectively. The results reflect great differences between the two sample series, particularly from the structural and optical point of view. These experiments point to the possibility of Te doping ZnO with the permanence of intrinsic defects, as well as the possibility of the formation of other Te solid phases when its content increases. The results and appreciable variations in the band gap transitions were detected from Photoluminescence (PL) measurements.

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Electronic structure and properties of Cu2-xS thin films: Dependence of phase structures and free-hole concentrations

Egbo

et al. 2022

Applied Surface Science

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Optoelectronic properties and doping of magnetron sputtered highly mismatched ZnO1-xTex alloy thin films

Cited by 4 publications

References 43 publications

Effects of oxygen flow ratio and thermal annealing on defect evolution of aluminum doped zinc oxide thin films by reactive DC magnetron sputtering

Effects of oxygen flow ratio and thermal annealing on defect evolution of aluminum doped zinc oxide thin films by reactive DC magnetron sputtering

ZnOTe Compounds Grown by DC-Magnetron Co-Sputtering

Electronic structure and properties of Cu2-xS thin films: Dependence of phase structures and free-hole concentrations

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