Improvement of Spectral Responsivity of Gold Nanoparticles via Laser Ablation at Different Laser Energies Deposited on Porous Silicon.

In this work, the synthesis and characterization of gold nanoparticles (Au NPs) were performed by pulsed laser ablation in liquid (PLAL) technique at different laser energies (500, 700, and 900 mJ) using Nd:YAG laser Q-switching wavelengths (1064 nm) and then deposited on porous silicon (PS). The PS was prepared using the electrochemical etching (ECE) method at an etching current density of 20 mA/cm2, an etching time of 15 min, and a hydrofluoric acid concentration of 25%.The structural, morphological, and optical properties of PS, Au NPs, and Au NPs/PS were determined using X-ray diffraction tests, FE-SEM analysis, UV–Vis spectroscopy, and photoluminescence (PL), respectively. The electrical characteristics of Al/Au NPs/PS/Si/Al heterojunctions have been determined with measurements of current–voltage (I-V) in the dark and under illumination. From the photo-detector measurements, the spectral responsivity curves included three regions; the first peak was due to absorption of the visible light by Au NPs. The second peak corresponds to the absorption of near-infrared light by the PS layer, and the third peak corresponds to the absorption edge of the Si substrate. The higher responsivity of the Au NPs/PS photo-detector was found to be 0.23 A/W for specimens prepared at laser energy of 500 mJ. [ABSTRACT FROM AUTHOR]