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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]

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.