Using Laser Duty Cycles for Modifying the Performance of Au-NPs/Si Nano Column Hot Spot SERS Sensors

Abstract

In the current study, the Si nano column layer via pulsed photo chemical etching with different laser pulse duty cycle 30 and 60% using short laser wavelength (405 nm) and laser intensity (100 mW/cm2) was formed and studied. Two types of Si nano column-based plasmonic Au-NP hot spot layers were synthesized and examined successfully as an efficient SERS layer for the detection of the ultra-low concentration of amoxicillin. Si nano columns exposed a great effect on the performance of the Au-NP hot spot SERS sensor showing a strong dependence on the density of the hot spot gaps within the sensitive layer. Enhancement factor (EF) of the Raman signal improved considerably with increasing the density of the hot spot gaps due to the coupling efficiency among the plasmonic Au-NPs and the molecules of amoxicillin within the hot spot regions. EF increased by about four orders of magnitude with decreasing the laser duty cycles due to the increase of the integrated plasmonic Au-NPs into the Si nano column layer.