Synthesis of MG-Al-Zn alloy nanoparticles via laser ablation and deposited on porous silicon for enhancement in the spectral responsivity

Abstract

In this research, the nanoparticles (NPs) of magnesium alloy (Mg–Al-Zn) were prepared using a laser ablation technique in a solution and then deposited on porous silicon. The structural characterization, electrical, and spectral properties of the nanoparticles deposited on the porous silicon were investigated. Firstly, the initial alloy was made as a bulk nanostructured alloy using high-pressure torsion processing at a grain size of 100 nm and then subjected to laser ablation at different powers of 500, 600, 700, 800, and 900 mJ, to produce metallic nanoparticles at a minimum particle size of 5.6 nm. Secondly, metallic nanoparticles were deposited on the porous silicon. Porous silicon (PS) was fabricated by photo-electrochemical etching (PECE) on an n-type crystalline silicon (c-Si) wafer with (111) orientation An etching current density of 20 mA/cm2 was applied for 15 min in an etchant medium of a 20% concentration of HF in the aforementioned etching process. The resultant particles were analyzed using the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and UV–visible spectrophotometry, as well as the electrical properties and photodetection studies were achieved here. The XRD data indicated the presence of Mg–Al-Zn NPs with a hexagonal wurtzite structure at a distinct diffraction peak at 28.5°. The morphological characteristics of Mg–Al-Zn nanoparticles deposited on the porous silicon indicated that the nanoparticle layer predominantly comprises particles with various shapes and sizes, randomly distributed on the porous silicon, with a relatively large particle size of an average of 24.15 nm when using a laser power of 500 mJ in the ablation process. The optical characteristics of the synthesized nanoparticles showed a rise in the value of the band gap with the augmentation of wavelength. Current–voltage (I-V) characterization showed there was an ohmic contact between deposited samples and electrodes. The photo-detector investigation yielded spectrum responsivity curves with three distinct zones. The initial region in the curve is ascribed to the assimilation of ultraviolet (UV) radiation by the Mg–Al-Zn NPs. The second region was attributed to the absorption of visible light by the PS layer, whereas the third peak resulted from the edge absorption of the Si substrate. The Mg–Al-Zn NPs/PS photodetector demonstrated a responsivity of 0.41 A/W when using a laser intensity of 900 mJ. The findings of this work open the way for future investigations to utilize such complex metallic systems as in Mg–Al-Zn NPs in photodetectors and optoelectronic devices utilizing complex metallic systems with advanced properties.

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Identifiers

ORCID for Nong Gao: orcid.org/0000-0002-7430-0319

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