arXiv subjects

R. P. Yadav

Publications and source records attributed to R. P. Yadav.

4 recordsLinked to original sources

arXiv2018

Humidity effects on evolution of CsI thin Films: Fractal studies of rough surfaces

The present work investigates the morphological, micro-structural, compositional and fractal analysis for CsI thin films in case of "as-deposited" and "1 hour humid air aged". The variation of grain sizes obtained from transmission electron microscopy (TEM) technique are found to be in the range of ~ 313 nm to ~ 1058 nm. The average grain size is found to increase after exposing to humidity. The experimental values of interplanner spacing are found to be less than the standard value which signifies that a compressive stress is acting in the film. The elemental compositions of CsI film has been investigated by the means of energy dispersive X-ray spectroscopy (EDAX) technique. The atomic percentage of Cs:I (1:1) is found to be increased by a factor of two after exposing to humidity. The surface morphology of CsI thin films is analyzed by the atomic force microscopy (AFM) for both cases. The fractal analysis is performed on the AFM micrographs. The autocorrelation function and height-height correlation function is used to study the correlation properties of surface and roughness exponent. It is found that the fractal dimension is affected after exposing to humidity.

physics.ins-det↗

arXiv2018

Growth evolution of self-affine thermally evaporated KBr thin films: A fractal assessment

In this article, fractal concepts were used to explore the thermally evaporated potassium bromide thin films of different thicknesses 200, 300, and 500 nm respectively; grown on aluminium substrates at room temperature. The self-affine or self similar nature of growing surfaces was investigated by autocorrelation function and obtained results are compared with the morphological envelope method. Theoretical estimations revealed that the global surface parameters such as, interface width and lateral correlation length are monotonically decreased with increasing film thickness. Also, from height profile and A-F plots, it has been perceived that irregularity/ complexity of growing layers was significantly influenced by thickness. On the other hand, the fractal dimension and local roughness exponent, estimated by height-height correlation function, do not suggest such dependency.

cond-mat.mtrl-sci↗

arXiv2017

Morphological characterization of Ge ion implanted SiO2 matrix using multifractal technique

200 nm thick SiO2 layers grown on Si substrates and Ge ions of 150 keV energy were implanted into SiO2 matrix with Different fluences. The implanted samples were annealed at 950 C for 30 minutes in Ar ambience. Topographical studies of implanted as well as annealed samples were captured by the atomic force microscopy (AFM). Two dimension (2D) multifractal detrended fluctuation analysis (MFDFA) based on the partition function approach has been used to study the surfaces of ion implanted and annealed samples. The partition function is used to calculate generalized Hurst exponent with the segment size. Moreover, it is seen that the generalized Hurst exponents vary nonlinearly with the moment, thereby exhibiting the multifractal nature. The multifractality of surface is pronounced after annealing for the surface implanted with fluence 7.5X1016 ions/cm^2.

cond-mat.mtrl-sci↗

arXiv2017

Fractal analysis of BaF2 thin films deposited on different substrates

Barrium fluoride (BaF2) thin films were prepared by electron beam evaporation technique at room temperature, on glass, Silicon and Aluminum substrates having thickness of 20 nm each. Its structural property and surface morphology were studied using glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM) respectively. It was found that grain size, average surface roughness and interface width changes with different substrates. Higuchi algorithm is applied for the fractal measure on AFM images.It was observed found that the fractal dimension varied from substrate to substrate.

cond-mat.mtrl-sci↗