Multifractal analysis of sputtered indium tin oxide thin film surfaces

Ţălu, Ștefan; Морозов, И. А.; Yadav, R. P.

doi:10.1016/j.apsusc.2019.04.170

Cited by 49 publications

(27 citation statements)

References 28 publications

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“…This can show that the in situ plasma sintering has shown to be effective, however, since the pressureless sintered target did not show the desired properties, it is possible that this is due to a dynamic equilibrium, which is knocked out of place by the plasma, leading to uneven sputtering of thin films by the target sintered at 1300°C. It must be emphasised that all the targets have been sputtered under similar sputtering conditions since the deposition conditions can affect the resulting surface characteristics (Ţălu et al ., 2018, 2019).…”

Section: Resultsmentioning

confidence: 99%

“…Since fractal dimension is indifferent towards grain size and aggregates, it may be a better indicator as a figure of merit for improving product characteristics in surface response methodology studies (Risović & Pavlović, 2013; Mitic et al ., 2019). Recent studies have investigated the effect of fractal dimension of optoelectrical materials (van Veen et al ., 2017; Rajabi Kalvani et al ., 2019; Ţălu et al ., 2019), and may even lead to self‐similar properties based on self‐similar grain morphology (Tavakoli & Jalili, 2014; García‐Cervantes et al ., 2017).…”

Section: Resultsmentioning

confidence: 99%

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Quantitative SEM characterisation of ceramic target prior and after magnetron sputtering: a case study of aluminium zinc oxide

Jahangiri

Kalvani

Shapouri

et al. 2020

Journal of Microscopy

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Summary Till now electron microscopy techniques have not been used to evaluate the plasma–target interactions undergone during the magnetron sputtering process. The destructive nature of this interaction severely alters the target microstructure. Utilising quantitative microscopy techniques can shed light on the complex plasma and solid‐state processes involved which can ultimately lead to improved functional thin film deposition. As a representative functional material, aluminium‐doped‐zinc oxide (AZO) is an upcoming alternative to conventional transparent electrode wherein the process optimisation is of great importance. In this paper, we evaluate the pre‐ and post‐sputter field emission scanning electron microscopy (FESEM) data for ceramic AZO target fabricated at three final sintering temperatures (1100°C, 1200°C and 1300°C). In all cases, grain boundaries are merged in addition to a visible reduction in the secondary phases which makes segmentation‐based image analysis challenging. Through surface statistics (i.e. fractal dimension, autocorrelation length, texture aspect ratio and entropy) as a function of magnification we can quantify the electron microscopy image of the microstructure. We show that the plasma–microstructure interaction leads to an increase in autocorrelation length, texture aspect ratio and entropy for the optimum AZO ceramic sputtering target sintered at 1200°C. Furthermore, a maximum reduction in fractal dimension span (as determined by exponential regression) is also observed for 1200°C. In addition to the evaluation of plasma effects on sintering, our approach can provide a window towards understanding the underlying thin film growth mechanisms. We believe that this technique can be applied to the defect characterisation of a wide range of polycrystalline ceramic sputtering targets (e.g. ITO, CZTS, GAZO and so on) with the ultimate goal of improving the magnetron sputtering process and the resulting functional thin film. Lay Description Magnetron sputtering allows scientists to make functional thin films on the order of the nanoscale. In this technique, atoms are plucked from a ‘target’ then placed onto a substrate forming a thin nanometric film: all thanks to magnets, a special power supply and the fourth state of matter (plasma). Understanding what is going on and how to make a ‘good’ thin film is important for making better light emitting diodes, solar cells and light sensors. Scientists use electron microscopy to see what is going on in the microstructure of the sputtered thin films to fine tune the sputtering recipe. Here, for the first time, we have applied electron microscopy to see the surface of the microstructure before and after magnetron sputtering. This will help us understanding the plasma–microstructure interaction allowing us to make more informed decisions when fine‐tuning the sputtering process to get improved thin films. This is a case study of aluminium‐doped zinc oxide (AZO) target that could potentially replace indium tin oxide (ITO), which is widely used as a tra...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Quantitative SEM characterisation of ceramic target prior and after magnetron sputtering: a case study of aluminium zinc oxide

Jahangiri

Kalvani

Shapouri

et al. 2020

Journal of Microscopy

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“…Over the last decades, various studies were performed about the 3-D (three-dimensional) surface microtexture of thin films that allow extracting different topographic characteristics quantitatively for new technological applications [13][14][15]. On the other hand, the microtexture of the 3-D surface can be characterized by stereometric [16][17][18], fractal [19][20][21], and multifractal [22][23][24][25] analyzes with a set of parameters that highlight the particular morphological characteristics of the surface. Atomic force microscopy (AFM), in combination with modern image processing techniques, offers advanced facilities for extracting particular topographic features of surfaces and highlights the local nanoscale configuration of 3-D complex surfaces [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Multifractal analysis of ZnO thin films doped with Mg deposited by sol-gel spin coating on a glass substrate

Ţălu

Boudour

Bouchama

et al. 2021

Preprint

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A multifractal analysis has been performed on the three-dimensional surface microtexture of the ZnO thin films doped with Mg deposited by sol-gel spin coating on glass substrates. The effects of Mg doping element with amounts of 0, 2, 4, and 5 % on structural and morphological properties of the coated films were investigated. From the X-ray diffraction pattern analysis, it was found that the obtained thin films had a polycrystalline hexagonal wurtzite structure with preferential c-axis orientation and increased grain size with increasing the Mg doping. From scanning electron microscopy (SEM) analysis, it can be concluded that the surface of coated thin films had dense and uniformly distributed grains of nanoscale without any cracks over all surfaces of coated firms. From atomic force microscope (AFM) analysis, it can be also concluded that the surface of coated thin films had a dense columnar grain growth uniformly distributed over the entire 1 µm ⋅ 1 µm - scanned area. The surface microtexture was characterized in terms of multifractal analysis.

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“…Indium tin oxide (ITO) is one of the most widely used transparent conducting oxides due to its low resistivity and excellent optical transparency [1][2][3][4]. ITO thin films can be prepared by various deposition techniques, such as thermal evaporation [5,6], radio-frequency (RF) magnetron sputtering [7,8] direct current (DC) magnetron sputtering [9][10][11][12], plasma ion-assisted evaporation [13], activated reactive evaporation [14], and sol-gel method [15]. The RF sputtering method is the most commonly used among all these methods because of the more compact structure and good transmittance of thin films prepared by this technique.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of electrical resistivity, residual stress and surface roughness of sputtering indium tin oxide films with different thicknesses

Tien¹,

Lin²,

Su³

2021

Optica Applicata

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This paper investigates the influence of film thickness on the electrical and mechanical properties of transparent indium tin oxide (ITO) thin films. Two groups of ITO thin films deposited on unheated substrates were prepared by the radio-frequency magnetron sputtering technique. The biaxial residual stress and surface roughness for two groups of ITO thin films were measured by a Twyman–Green interferometer and a Linnik microscopic interferometer, respectively. The electrical resistivity of the ITO films was measured by a four-point probe apparatus, the thickness was determined mechanically with a profilometer. The measurement results show that the average resistivity of ITO thin films decreases with increasing the deposited thickness. The compressive residual stress in the ITO thin films decreases with increasing the deposited thickness. We also find that an anisotropic stress in the two groups of ITO films is more compressive in a certain direction. The RMS surface roughness in the two groups of ITO films is less than 1 nm.

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Multifractal analysis of sputtered indium tin oxide thin film surfaces

Cited by 49 publications

References 28 publications

Quantitative SEM characterisation of ceramic target prior and after magnetron sputtering: a case study of aluminium zinc oxide

Quantitative SEM characterisation of ceramic target prior and after magnetron sputtering: a case study of aluminium zinc oxide

Multifractal analysis of ZnO thin films doped with Mg deposited by sol-gel spin coating on a glass substrate

Evaluation of electrical resistivity, residual stress and surface roughness of sputtering indium tin oxide films with different thicknesses

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