WO3 nanoparticles-embedded porous silicon: Dual-function materials synthesized via laser ablation and electrochemical etching for advanced photodetection and gas sensing applications

Abstract

In light of their outstanding physical and chemical traits, nanostructured devices have attracted significant attention. In light of their outstanding physical and chemical traits, nanostructured devices have attracted significant attention. The manipulation of the dimensions and morphology of nanostructured surfaces could precisely adjust these characteristics. In this work, porous silicon (PSi) was synthesized through a laser-assisted electrochemical etching method. The porous silicon was embedded with tungsten trioxide WO₃ nanoparticles (NPs), which were synthesized using liquid phase laser ablation at different laser fluences. X-ray diffraction (XRD) analysis verified the synthesis of tungsten oxide nanoparticles in a crystalline form featuring a monoclinic structure, which was integrated into the porous silicon matrix. Investigations utilizing scanning electron microscopy (SEM) and transmission electron microscopy (TEM) exhibited the development of spherical tungsten oxide nanoparticles, featuring diameters ranging from 110 to 153 nm, upon the laser fluence employed. SEM analysis further showed that the average pore diameter of the porous silicon was 1.6 μm, with the tungsten oxide nanoparticles embedded inside the pores. Optical measurements indicated that the tungsten oxide energy gap was 3.2 eV at a laser fluence of 51 J/cm² and rose to 3.55 eV as the laser fluence increased to 71 J/cm². Zeta potential studies indicated that the nanoparticles formed at 61 J/cm² were stable. The optoelectronic properties of WO₃ nanoparticle-embedded PSi/c-Si heterojunction photodetectors fabricated at different laser fluences were also investigated. A responsivity of 1.35 A/W was attained at a wavelength of 450 nm when the device was fabricated using 61 J/cm² laser fluence. The WO₃-embedded PSi gas sensor synthesized at a 61 J/cm² energy fluence exhibited the highest CO gas sensitivity, with a 63 % response at 20.2 ppm.