AZO Thin Films by Sol-Gel Process for Integrated Optics

Znaidi, L.; Touam, Tahar; Vrel, D.; Souded, Nacer; Yahia, Sana Ben; Brinza, Ovidiu; Fischer, A.; Boudrioua, Azzedine

doi:10.3390/coatings3030126

Cited by 101 publications

(40 citation statements)

References 54 publications

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“…Al-and Ga-ZnO films grown by PLD, molecular beam epitaxay and chemical vapor deposition methods have shown carrier concentrations on the order of 10 20 cm -3 . 4,5 Various wet chemistry coating techniques [6][7][8][9][10] have also been applied to synthesize ZnO thin films, but high levels of intrinsic defects make it difficult to control the film a Corresponding author: faselim@bgsu.edu properties. Despite considerable research on sol-gel ZnO films, no detailed structural information on film layering, thickness uniformity, and defect nature are available.…”

Section: Introductionmentioning

confidence: 99%

“…Despite considerable research on sol-gel ZnO films, no detailed structural information on film layering, thickness uniformity, and defect nature are available. In this work we use the sol-gel and spin coating method [7][8][9][10][11] to synthesize ZnO films and introduce in them extrinsic shallow donors such as Al 3+ and Ga 3+ through precursor solutions, followed by various post processing heat treatment techniques to tune the film properties. Group III elements such as Al 3+ and Ga 3+ have similar ionic radius to that of Zn 2+ and thus can easily replace it with little effect on the lattice structure.…”

Section: Introductionmentioning

confidence: 99%

“…Group III elements such as Al 3+ and Ga 3+ have similar ionic radius to that of Zn 2+ and thus can easily replace it with little effect on the lattice structure. 8,12,13 The characterization section of the article focuses on relating the electrical properties of the fabricated films to their atomic structures and defects using data obtained from high resolution scanning electron microscopy (SEM) and positron annihilation spectroscopy (PAS) techniques. 14 The Doppler broadening of positron annihilation (DBPA) measurements presented in this work reveal strong passivation of Zn vacancy related defects by hydrogen that immensely alters the electrical conductivity of the films.…”

Section: Introductionmentioning

confidence: 99%

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Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies

et al. 2016

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Undoped and Ga-and Al-doped ZnO films were synthesized using sol-gel and spin coating methods and characterized by X-ray diffraction, high-resolution scanning electron microscopy (SEM), optical spectroscopy and Hall-effect measurements. SEM measurements reveal an average grain size of 20 nm and distinct individual layer structure. Measurable conductivity was not detected in the unprocessed films; however, annealing in hydrogen or zinc environment induced significant conductivity (∼10 −2 Ω.cm) in most films. Positron annihilation spectroscopy measurements provided strong evidence that the significant enhancement in conductivity was due to hydrogen passivation of Zn vacancy related defects or elimination of Zn vacancies by Zn interstitials which suppress their role as deep acceptors. Hydrogen passivation of cation vacancies is shown to play an important role in tuning the electrical conductivity of ZnO, similar to its role in passivation of defects at the Si/SiO2 interface that has been essential for the successful development of complementary metal-oxide-semiconductor (CMOS) devices. By comparison with hydrogen effect on other oxides, we suggest that hydrogen may play a universal role in oxides passivating cation vacancies and modifying their electronic properties. © 2016 Author(s)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies

et al. 2016

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“…A sol-gel dip-coating method has been developed recently for photovoltaic as well as magnetic devices applications [13] [14]. The sol-gel method is considered as an adequate procedure for high purity and homogeneous films [15], based on the hydrolysis and the polycondensation of metal organic precursors, such as metal alkoxides [16]. This deposition technique has been the Scientifics' main interest last for few years due to the low temperature processing [17].…”

Section: Introductionmentioning

confidence: 99%

Influence of Sn Low Doping on the Morphological, Structural and Optical Properties of ZnO Films Deposited by Sol Gel Dip-Coating

Zegadi¹,

Abdelkebir²,

Chaumont³

et al. 2014

AMPC

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In this work, Undoped Zinc Oxide (ZnO) and Sn-doped Zinc Oxide (ZnO:Sn) films have been deposited by sol-gel dip coating method, where the Sn/Zn atomic ratio was 3% and 5% in the solution. The effects of Sn incorporation on morphological, structural and optical properties of ZnO films were investigated. The Scanning Electron Microscopy (SEM) showed that the morphological surface of the films was affected by Sn low doping. The X-Ray Diffraction (XRD) patterns showed that all films have polycrystalline structures, and the doping incorporation has not lead to substantial changes in the structural characteristics of ZnO films. The crystallite size was calculated using the well-known Scherrer's formula and found to be in the range of 23 -40 nm. The measurements from UV-Visible Spectrophotometer (U-Vis) indicated that the highest average optical transmittance in the visible region was related to Undoped ZnO film, then the optical band gap and Urbach energy values of thin films were calculated. The X-Ray Photoelectron Spectroscopy (XPS) has demonstrated that Sn is incorporated in ZnO lattice.

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“…Among the chemical solution based methods are techniques, such as spray pyrolysis [64,65] and sol-gel methods [66,67]. In spray pyrolysis, fine droplets of a solution of precursors such as zinc acetate and aluminium chloride are sprayed onto a heated substrate.…”

Section: Chemical Solution Based Methodsmentioning

confidence: 99%

Deposition of Al-doped ZnO films by high power impulse magnetron sputtering

Mickan¹

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Transparent conducting oxides (TCOs) are an important class of materials with many applications such as low emissivity coatings, or transparent electrodes for photovoltaics and flat panel displays. Among the possible TCO materials, Al-doped ZnO (AZO) is studied due to its relatively low cost and abundance of the raw materials. Thin films of AZO are commonly produced using physical vapour deposition techniques such as magnetron sputtering. However, there is a problem with the homogeneity of the films using reactive direct current magnetron sputtering (DCMS). This homogeneity problem can be related to the bombardment of the growing film with negative oxygen ions, that can cause additional acceptor defects and the formation of insulating secondary phases. In this work AZO films are deposited by high power impulse magnetron sputtering (HiPIMS), a technique in which high instantaneous current densities are achieved by short pulses of low duty cycle.In the first part of this thesis, the possibility to improve the homogeneity of the deposited AZO films by using HiPIMS is demonstrated. This improvement can be related to the high instantaneous sputtering rate during the HiPIMS pulses, so the process can take place in the metal mode. This allows for a lower oxygen ion bombardment of the growing film, which can help to avoid the formation of secondary phases. Another problem of AZO is the stability of the properties in humid environments. To assess this problem, the degradation of the electrical properties after an aging procedure was investigated for films deposited by both DCMS and by HiPIMS. A method was proposed, to restore the properties of the films, using a low temperature annealing under N 2 atmosphere. The improvement of the electrical properties of the films could be related to a diffusion process, where water is diffusing out of the films. Then, the influence of the substrate temperature on the properties of AZO films deposited by HiPIMS was studied. The electrical, optical and structural properties were found to improve with increasing substrate temperature up to 600• C. This improvement can be mostly explained by the increase I in crystalline quality and the annealing of defects. Finally, the deposition of AZO films on flexible PET substrates was investigated. The films are growing as a thick porous layer of preferentially c-axis oriented columns on top of a thin dense seed layer. The evolution of the sheet resistance of the films after bending the films with different radii was studied. There is an increase in the sheet resistance of the films with decreasing bending radius, that is less pronounced for thicker films. II Populärvetenskaplig sammanfattningFör många viktiga tillämpningar i vårt moderna liv, såsom skärmar till mobiltelefoner eller solceller, är det nödvändigt att ha ett transparent material som har en elektrisk ledningsförmåga. Att både vara transparent och vara elektriskt ledande är en ovanlig materialegenskap. Material som är elektriskt ledande, såsom metaller, är vanligtvis inte transp...

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AZO Thin Films by Sol-Gel Process for Integrated Optics

Cited by 101 publications

References 54 publications

Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies

Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies

Influence of Sn Low Doping on the Morphological, Structural and Optical Properties of ZnO Films Deposited by Sol Gel Dip-Coating

Deposition of Al-doped ZnO films by high power impulse magnetron sputtering

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