Controllable formation of plasmonic gold nanoparticles by pulsed laser–induced etching

Abstract

This work discusses the preparation and formation of macro porous silicon (PSi) with silicon nano pillars; synthesized via laser–induced etching. The role of laser pulse duty cycle (10–100%) was investigated for silicon nano pillars samples creation using laser diode; characterized by its short wavelength (405 nm) and high laser intensity (500 mW/cm2). Morphological and spectroscopic aspects of the Si nanocrystallite sizes and plasmonic Au–NP, surface topography, roughness and thickness of the created layer were investigated by the scanning probe microscopy, photoluminescence measurements, the analysis of (FESEM) images and (XRD) patterns. The results revealed well-regulated Si nano pillars layers after adjusting the laser duty cycle under the same laser intensity and etching time. The histogram of Si nano pillars sizes, surface roughness and altitude of nano pillars within macro PSi created at 20% laser duty cycle showed specific characteristics; due to the minimal heat accumulation within the pillars and limited probability of damaging the pillars’ morphological aspects. The Si nano pillars were employed to synthesize and control the plasmonic features of Au-NPs. The histogram of hotspot regions and plasmonic Au-NPs sizes and their specific surface areas and grain size showed well-controlled structures after adjusting the laser pulse duty cycle.