Evolution of surface topography and optical band gap of ZnO film deposited on NiO/Si(100)

Das, Pankaj Kumar; Biswal, R.; Choudhary, R. J.; Ganesan, V.; Mallick, P.

doi:10.1002/sia.6365

Cited by 10 publications

(8 citation statements)

References 35 publications

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“…The obtained values lie well within the previously reported bandgap values (3.6À4.0 eV) for NiO thin films. [32][33][34][35] The higher bandgap of the films grown at 400 and 500 C can be attributed to nonstoichiometry, higher dislocation densities, and extended defect states, [36] as witnessed from previous measurements.…”

Section: Resultsmentioning

confidence: 53%

Temperature‐Driven Perturbations in Growth Kinetics, Structural and Optical Properties of NiO Thin Films

Mishra¹,

Barthwal²,

Tak³

et al. 2021

Physica Status Solidi (a)

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Recent years have witnessed a growing demand in the improvement of nanostructured metal oxides with p-type conductivity. Nickel oxide (NiO) is a naturally grown p-type metal-oxide semiconductor pursuing direct wide bandgap (from 3.6 to 4 eV), moderate conductivity, good chemical stability, high transmittance, and excellent optoelectronic properties. [1] It crystallizes in sodium chloride (NaCl)-type face-centered cubic (FCC) structure and exhibits maximum hole conductivity along (111) direction. [1][2][3] Being a transparent p-type semiconducting oxide, NiO offers potential application in the domain of perovskite solar cells (transparent electrodes), visible blind photodetection, solid-state gas sensing and electrochromic displays, etc. [2][3][4][5] Despite its technological importance, the growth of device-grade NiO thin films has remained a challenging task, mainly attributed to its low conductivity. To date, numerous studies on the growth of NiO via various physical and chemical methods including magnetron sputtering, [6,7] plasma-enhanced chemical vapor deposition (PECVD), [8] pulsed laser deposition (PLD), [9] thermal evaporation, [10] spray pyrolysis, [11] sol-gel processing, [12] etc. have been reported so far. However, among the various aforementioned methods, radio-frequency (RF) magnetron sputtering is the most common and a widely used technique for the growth of NiO thin films. [13][14][15][16][17][18] Literature reports that growth parameters play a critical role in governing the properties of NiO films grown by RF magnetron sputtering. [13][14][15][16]19] Modifications in growth parameters may introduce various defects such as structural points defects, dislocations, or perturbation-induced ingap states, [13,15] affecting the structural, optical, and electrical properties of the grown NiO films. Ahmed et al. [16] observed that the growth of NiO is substrate dependent and that the inherent material properties depend strongly on the types of substrate (Si, GaAs, PET, etc). In contrast, Grilli et al. [19] reported that RF power and sputtering gas significantly influence the resistivity (from 10 À2 to 10 À1 Ω-cm) and transmittance of the grown NiO films. A recent study by Turgut et al. [20] said that oxygen partial pressure not only changes the structural and morphological properties, but it also influences the oxidation state of nickel, leading to significant variation in the performance of NiO-based hydrogen sensors. [20] In a recent report, Dhull et al. [21] also demonstrated that substrate temperature can play a significant role in tailoring the morphology of NiO films, leading to perturbation in charge transfer characteristics. However, few other studies were also conducted to explore the influence of growth temperature on structural, optical, morphological, and device applications of NiO thin films, but the extent of study was limited to a lower growth temperature, that is, up to 300 C only. [22][23][24][25] It implies that growth temperature significantly

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Section: Resultsmentioning

confidence: 53%

Temperature‐Driven Perturbations in Growth Kinetics, Structural and Optical Properties of NiO Thin Films

Mishra¹,

Barthwal²,

Tak³

et al. 2021

Physica Status Solidi (a)

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“…These δ values may give an insight into the surface transport mechanism during the thin film growth process. It represents the surface transport via respectively, viscous flow, evaporationcondensation, volume diffusion and surface diffusion for its values of 1, 2, 3, and 4 [29,55]. In the present case, the δ value after annealing the films at 300 °C, 400 °C and 500 °C were found to be respectively, 1.59±0.01, 1.81±0.01 and 1.82±0.02.…”

Section: Annealing Effect On Power Spectral Density and Fractalmentioning

confidence: 56%

“…Only a few researchers have studied thin film surface morphology with the help of the fractal geometrical concept and have correlated various physical and growth properties with the fractal parameters. Power spectral density (PSD) analysis has been used by Das et al [29] to analyze the effect of initial microstructures on the evolution of surface features of the ZnO thin films deposited on different NiO/Si(100) substrates. Raoufi [30] observed the evolution of the fractal parameters with the change in the surface topography as calculated using the PSD method in ITO thin films annealed at different temperatures.…”

Section: Introductionmentioning

confidence: 99%

Power spectral density-based fractal analysis of annealing effect in low cost solution-processed Al-doped ZnO thin films

Ghosh¹,

Pandey²

2019

Phys. Scr.

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Thin films of aluminium-doped zinc oxide (Al:ZnO) have been deposited using the sol-gel spin coating method and annealed at 300 °C, 400 °C, and 500 °C. The structural phase purity of the annealed films has been confirmed by the glancing angle x-ray diffraction patterns. The average microcrystalline size and residual microcrystalline stress have been calculated from it. It is observed that the average microcrystalline size increases and the residual microcrystalline compressive stress first increases and then decreases with increasing annealing temperature from 300 °C to 500 °C. The conventional surface roughness calculations and the power spectral density (PSD)-based fractal computations of the AFM micrographs have been carried out. The values of the power-law exponent demonstrate the underlying mechanism of the films' residual surface growth. All the annealed films have a combined surface transport mechanism of viscous flow and evaporation-condensation. However, evaporation-condensation becomes dominant at the higher annealing temperatures of 400 °C and 500 °C. The spatial and vertical anisotropy of thin film surface topography has been quantified in a scale-invariant and generalized manner with the help of fractal geometrical analysis. The values of the fractal dimensions and Hurst exponents indicate that the vertical roughness of the films increases and the spatial self-similarity decreases with increasing annealing temperature. It is noteworthy that the Hurst exponent can alone depict the complexity of a thin film surface, whereas in conventional techniques at least three parameters are necessary for this. The fractal dimension increases with increasing average grain size and annealing temperature. Consequently, overall surface complexity increases with increasing annealing temperature. Thus, the fractal analysis can find its application in the predictability and assessment of surface topography. Also, various physical properties of films may be correlated with the fractal parameter of thin film surfaces in future works for micro and nano device fabrications.

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“…Figure b indicates that there is an increase in band gap from 3.01 eV to 3.17 eV when there is the increase in pH from 11 to 12, implying a decrease in particle size. It is observed that band gaps of ZnO NPs are slightly different than reported values …”

Section: Resultsmentioning

confidence: 99%

pH‐Transformed ZnO‐NPs /NaPTS: The First Room‐Temperature Brisk Synthesis of Flavanones in Aqueous Medium

Shinde¹,

Kamble²,

Pore

et al. 2018

ChemistrySelect

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We investigated pH transformed ZnO NPs viz ZnO nanobullets and ZnO nanograins at pH 11 and 12 respectively, synthesized by co‐precipitation method. The structural, morphological, chemical, compositional and optical properties of synthesized ZnO NPs were analysed by using X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray Spectroscopy (EDAX) and Ultra‐Violate Visible spectroscopy (UV‐Vis). The Noteworthy feature of ZnO NPs in presence of NaPTS leads a speedy formation of flavanones from the reaction of an aldehyde and o‐hydroxy acetophenone. Thus, it imparted the first room‐temperature brisk synthesis of flavanones in an aqueous medium.

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Evolution of surface topography and optical band gap of ZnO film deposited on NiO/Si(100)

Cited by 10 publications

References 35 publications

Temperature‐Driven Perturbations in Growth Kinetics, Structural and Optical Properties of NiO Thin Films

Temperature‐Driven Perturbations in Growth Kinetics, Structural and Optical Properties of NiO Thin Films

Power spectral density-based fractal analysis of annealing effect in low cost solution-processed Al-doped ZnO thin films

pH‐Transformed ZnO‐NPs /NaPTS: The First Room‐Temperature Brisk Synthesis of Flavanones in Aqueous Medium

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