A novel plasma-based method for synthesis of As-Se-Te films: Impact of plasma parameters on the structure, composition, and optical properties

Kudryashov, Mikhail; Mochalov, Leonid; Nezdanov, Aleksey; Корнев, Р. А.; Логунов, А. А.; Усанов, Д. А.; Машин, А. И.; Filpo, Giovanni De; Gogova, D.

doi:10.1016/j.spmi.2019.01.035

Cited by 9 publications

(7 citation statements)

References 29 publications

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“…The peak located at 221 cm −1 is due to the As-Se vibration of pyramidal AsSe 3/2 symmetric stretching units (Němec et al 2005). However, there is a shoulder peak at 241 cm −1 which is assigned to the vibrations of AsSe structural units (Kudryashov et al 2019). The intensity of these two peaks increased for the 423 K annealed film while it decreased for the 523 K annealed film.…”

Section: (B) Raman Analysismentioning

confidence: 97%

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Sahoo¹,

Priyadarshini²,

Dandela³

et al. 2021

Opt Quant Electron

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The present work reports the amorphous-crystalline phase transformation in thermally evaporated As 50 Se 50 thin films upon annealing at below T g (423 K) and above T g (523 K). The structural transition was probed by XRD, Raman and X-ray photoelectron spectroscopy. The composition and surface morphology were probed by EDS and FESEM techniques. The transmittance and reflectance spectra over the wavelength range 500 nm-1200 nm were used to deduce the optical parameters. The various optical parameters of the as-prepared and annealed As 50 Se 50 thin films were estimated and discussed in terms of density of defect states and disorders. The indirect optical energy gap decreased for the 423 K annealed film and abruptly increased for 523 K annealed film as compared to the as-prepared film. The Swanepoel envelope method, WDD model, and Sellemeire postulates were employed for the analysis of refractive index, static refractive index, oscillator energy, dispersion energy, oscillator wavelength and dielectric constant. The changes in the linear and nonlinear properties showed opposite behavior for the two annealed films. The non-linear refractive index and 3rd order susceptibility were found to be increased for 423 K annealed film and decreased for the 523 K annealed film. The optical as well as the electrical conductivity changed with annealing and the electrical susceptibility increased for 523 K annealed film. The tunable optical properties can be applied for several optoelectronic applications.

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Section: (B) Raman Analysismentioning

confidence: 97%

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Sahoo¹,

Priyadarshini²,

Dandela³

et al. 2021

Opt Quant Electron

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“…Panel ii of Figure a shows the Raman data of the films, including various peaks at different wavenumbers. The peak at 69 cm –1 is caused by the presence of Te structural units . This is also due to the atomic mass of Te being higher than that of Se.…”

Section: Resultsmentioning

confidence: 99%

Thermal Annealing-Induced Transformation of Structural, Morphological, Linear, and Nonlinear Optical Parameters of Quaternary As₂₀Ag₁₀Te₁₀Se₆₀ Thin Films for Optical Applications

Das¹,

Senapati²,

Alagarasan

et al. 2022

ACS Appl. Opt. Mater.

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This work focuses on the structural, optical, and morphological modifications in As 20 Ag 10 Te 10 Se 60 quaternary thin films that are ∼800 nm thick upon thermal annealing at different temperatures. The structure is analyzed by Xray diffraction that reveals the phase transformation (amorphous to crystalline) due to annealing. This material's phase transition enables it to be used in memory device applications. The increase in particle size is confirmed by field emission scanning electron microscopy of the surface. The increase in particle size signifies the agglomeration occurs at higher annealing temperatures. The optical transmittance shows a red shift toward a lower photon energy as recorded by the ultraviolet−visible spectrometer. The optical bandgap of the films decreases (1.84 to 1.72 eV), whereas the refractive index increases as calculated from the Swanepoel method. The decrease in the bandgap is attributed to the increases in the localized states. The amorphous to crystalline transition results in a significant increase in the third-order nonlinear susceptibility (from 4.524 × 10 −11 to 14.146 × 10 −11 esu). The nonlinear refractive index is found to increase from 5.385 × 10 −10 to 14.786 × 10 −10 esu upon annealing. The static and high-frequency dielectric constant increases with the increase in oscillator and dispersion energy. The observed changes are explained on the basis of phase transformation and the density of defect states. The enhanced value of the nonlinear refractive index with a reduced optical electronegativity and carrier concentration with annealing is useful for nonlinear optical devices.

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“…The grain boundaries are indistinguishable. This can be attributed to the fact that sputtering power leads to a ‘spark plasma sintering’‐like treatment within the sputtering chamber, leading to a more homogeneous layer (Kudryashov et al ., 2019; Chen et al ., 2020). Based on a statistical analysis of the pre‐ and post‐sputter images we will demonstrate that the secondary phase particles are effectively suppressed by the plasma in 1200°C, whereas they are still evident in the 1300°C target.…”

Section: Resultsmentioning

confidence: 99%

“…For 1200°C, not only has the fractal dimension reduced, but also the fractal dimension is less dependent upon magnification. This may suggest that the fractal features of the structure are scale independent and thus a more homogenous microstructure is achieved as part of the plasma–microstructure interaction (Kudryashov et al ., 2019). This is further verified by Figure 6(D) where the reductions both span and half‐life in the postsputter FESEM images are maximum.…”

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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A novel plasma-based method for synthesis of As-Se-Te films: Impact of plasma parameters on the structure, composition, and optical properties

Cited by 9 publications

References 29 publications

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Thermal Annealing-Induced Transformation of Structural, Morphological, Linear, and Nonlinear Optical Parameters of Quaternary As₂₀Ag₁₀Te₁₀Se₆₀ Thin Films for Optical Applications

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

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A novel plasma-based method for synthesis of As-Se-Te films: Impact of plasma parameters on the structure, composition, and optical properties

Cited by 9 publications

References 29 publications

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Investigation of amorphous-crystalline transformation induced optical and electronic properties change in annealed As50Se50 thin films

Thermal Annealing-Induced Transformation of Structural, Morphological, Linear, and Nonlinear Optical Parameters of Quaternary As20Ag10Te10Se60 Thin Films for Optical Applications

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

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Thermal Annealing-Induced Transformation of Structural, Morphological, Linear, and Nonlinear Optical Parameters of Quaternary As₂₀Ag₁₀Te₁₀Se₆₀ Thin Films for Optical Applications