Effect of Grazing Angle Cross-Ion Irradiation on Ag Thin Films.

Manish Kumar,Praveen Kumar,Vandana Panchal,Abhishek Pathak,Teena Jangid

doi:10.1186/s11671-016-1665-5

Abstract

Apart from the spherical shape, control over other shapes is a technical challenge in synthesis approaches of nanostructures. Here, we studied the effect of grazing angle cross-irradiation Ag thin films for the nanostructures evolution from a top-down approach. Ag thin films of different thicknesses were deposited on Si (100) and glass substrates by electron beam evaporation system and subsequently irradiated at grazing angle ions by 80 keV Ar+ in two steps (to induce effectively a cross-ion irradiation). Pristine films exhibited dense and uniform distribution of Ag nanoparticles with their characteristic surface plasmon resonance-induced absorption peak around 420 nm. When the film surfaces were treated with cross-grazing angle irradiation of Ar ions with varying effective fluences from 0.5 × 1017 ions/cm2 to 2.0 × 1017 ions/cm2, it was found that fluence values governed the competition of sputtering and sputter re-deposition of Ag. As a result, lower irradiation fluence favoured the formation of cone-like nanostructures, whereas high fluence values demonstrated dominant sputtering. Fluence-dependent modification of surface features was studied through the Fourier transform infrared spectroscopy and the Rutherford backscattering spectroscopy. Theoretical justifications for the underlying mechanisms are presented to justify the experimental results.

Highlights

Ag nanostructures, owing to the strong coupling of surface plasmons with the incident light, exhibit interesting properties, e.g. photochemical activity [1], antibacterial activity [2], linear [3] and nonlinear optical properties [4] and surface-enhanced Raman scattering [5]
The first step involves the deposition of the Ag thin film over the Si substrate using electron beam physical vapour deposition system
The incident ion beam induced the ripple-like pattern over the Ag surface

Summary

Introduction

Ag nanostructures, owing to the strong coupling of surface plasmons with the incident light, exhibit interesting properties, e.g. photochemical activity [1], antibacterial activity [2], linear [3] and nonlinear optical properties [4] and surface-enhanced Raman scattering [5]. The gradient of the atomic flux parallel to the surface, generated by ion bombardment may lead to net smoothening for normal incidence conditions, whereas for larger incidence angles, roughening and ripple formation can occur [21,22,23,24]. In this way, sputtering of the ion beam sometime results in a smooth surface and some time in a rough surface. Irradiation may induce well-ordered topographies, like ripples [22,23,24,25], dots [26], cones [27] and nanowires [28] These nanoscale periodic structures have found many potential applications. Ripple patterns have found applications in plasmonics and nanoscale magnetism as templates for growth of functional thin films [28, 29], whereas nanodotand nanowire-type arrays are reported for fabricating trace

Methods

Results

Conclusion