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Pt/GaN Schottky barrier diodes and GaN epitaxial layers on sapphire substrates were studied under swift heavy ion irradiation using 100 MeV O7+ ions having fluences in the range of 1 × 1010–6.4 × 1013 ions/cm2. It was observed that ideality factor, Schottky barrier height, and series resistance increased, while carrier concentration decreased with increasing ion fluence. The ex situ measurements, such as x-ray diffraction and UV–Vis spectroscopy, revealed that GaN layers exhibit negligible variation in structural and bandgap characteristics after irradiation with oxygen ions. The cross-sectional transmission electron microscopy images of the GaN epitaxial layer irradiated at 5 × 1012 ions/cm2 confirmed the absence of irradiation-induced tracks or defect clusters, indicating only point defects that can act as charge traps without structural damage. [ABSTRACT FROM AUTHOR]

The Au partially embedded nanostructure (PEN) is synthesized by ion irradiation on an Au thin film deposited on a glass substrate using a 50 keV Ar ion. Scanning electron microscopy results show ion beam‐induced restructuring from irregularly shaped nanostructures (NSs) to spherical Au NSs, and further ion irradiation leads to the formation of well‐separated spherical nanoparticles. Higuchi's algorithm of surface analysis is utilized to find the evolution of surface morphology with ion irradiation in terms of the Hurst exponent and fractal dimension. The Au PEN is evidenced by Rutherford backscattering spectrometry and optical studies. Also, the depth of the mechanism behind synthesized PEN is explained on the basis of theoretical simulations, namely, a unified thermal spike and a Monte Carlo simulation consisting of dynamic compositional changes (TRIDYN). Another set of plasmonic NSs was formed on the surface by thermal annealing of the Au film on the substrate. Glucose sensing has been studied on the two types of plasmonic layers: nanoparticles on the surface and PEN. The results reveal the sensing responses of both types of plasmonic layers. However, PEN retains its plasmonic behavior as the NSs are still present after washing with water, which demonstrates the potential for reusability. Research Highlights: Synthesis of PENs by ion irradiationUtilization of Higuchi's algorithm to explore the surface morphology.Unified thermal spike and TRIDYN simulations being used to explain the results.Glucose is only used as a test case for reusability of substrate. [ABSTRACT FROM AUTHOR]

The unique mechanical properties of Tungsten Carbide (WC), such as fracture toughness, exceptional hardness, high melting temperature, outstanding thermal stability, anti-oxidation qualities fatigue and creep resistance, have made it a suitable industrial material for different applications. It is also considered to be a promising material for coating on plasma-facing walls in a Tokamak reactor. The aim of the present work is to study the effect of varying substrate temperature, concentration of tungsten (W) and annealing in the structural properties of WC films. The WC films are deposited on a silicon substrate at different substrate temperatures viz. RT (300 K), 400, 500, 600 and 700 K using DC magnetron sputtering. W-rich WC films were deposited keeping the power of WC constant (100 Watt) and varying W powers (10 Watt, 20 Watt, 30 Watt, 40 Watt) at room temperature. Later, these W-rich WC films were annealed at 800°C in a reducing atmosphere. Glancing incidence X-ray diffraction (GIXRD) and Raman spectroscopy of the films are performed for structural analysis. GIXRD of the WC films reveals that as-deposited RT films are amorphous. However, films which are either deposited at elevated substrate temperature or are annealed are crystalline. This is confirmed by Raman's measurements. It also indicates the presence of disorder and nanocrystalline phases due to temperature variations. [ABSTRACT FROM AUTHOR]

We present the morphological evolution and fractal characterizations of CaF2 thin-film surfaces modified by bombardment with 100 MeV Au+8 ions at various fluences. Atomic force microscopy (AFM) combined with line profile and two-dimensional power spectral density (2D-PSD) analysis was utilized to investigate the evolution of surface morphology as a function of fluence. The AFM images were utilized to investigate the relationship between fractal dimension, roughness exponent, lateral correlation length, and ion fluence. The surface erosion owing to sputtering was depicted using Rutherford backscattering spectrometry. The structural characteristics' dependency on fluence was explored with the help of glancing angle x-ray diffraction measurements on virgin and irradiated samples. Tensile stress calculated using a peak shift in the glancing angle x-ray diffractogram showed an increase in tensile stress with fluence that caused the surface to crack after the fracture strength of the surface was crossed. 2D-PSD analysis signified the role of sputtering over surface diffusion for the observed surface modifications. Fractal dimensions first increased and then decreased with ion fluence. The lateral correlation length decreased, while the roughness exponent increased with fluence after the threshold value. [ABSTRACT FROM AUTHOR]

We present the morphological evolution and fractal characterizations of CaF 2 thin-film surfaces modified by bombardment with 100 MeV Au +8 ions at various fluences. Atomic force microscopy (AFM) combined with line profile and two-dimensional power spectral density (2D-PSD) analysis was utilized to investigate the evolution of surface morphology as a function of fluence. The AFM images were utilized to investigate the relationship between fractal dimension, roughness exponent, lateral correlation length, and ion fluence. The surface erosion owing to sputtering was depicted using Rutherford backscattering spectrometry. The structural characteristics' dependency on fluence was explored with the help of glancing angle x-ray diffraction measurements on virgin and irradiated samples. Tensile stress calculated using a peak shift in the glancing angle x-ray diffractogram showed an increase in tensile stress with fluence that caused the surface to crack after the fracture strength of the surface was crossed. 2D-PSD analysis signified the role of sputtering over surface diffusion for the observed surface modifications. Fractal dimensions first increased and then decreased with ion fluence. The lateral correlation length decreased, while the roughness exponent increased with fluence after the threshold value.