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Nanostructured photodetectors have garnered great attention due to their enriched electronic and optical properties. In this work, we aim to fabricate a high-performance CeO2/Si photodetector by growing a CeO2 nanostructure film on a silicon substrate using the pulsed laser deposition (PLD) technique at different laser energy densities. The impact of laser energy density and the number of pulses on the morphological, optical, and electrical properties was studied. Field emission scanning electron microscopy (FESEM) results show that the CeO2 film has a spherical grain morphology with an average grain size ranging from 33 to 54 nm, depending on the laser energy density. The film deposited at various numbers of laser pulses also has spherical grains with an average grain size ranging from 39 to 54 nm, depending on the number of pulses. The optical properties of the CeO2 film showed that the optical energy gap of the films decreased from 3.5 to 3 eV as the laser energy density increased from 63.66 to 101.86 J/cm2. The photoluminescence (PL) spectra of the nanostructured CeO2 film reveal that the main emission peaks were observed at 682 nm when excited at 450 nm. The effect of laser energy density on the electrical properties, including carrier concentration, mobility, and current-voltage characteristics under dark and illuminated conditions, was investigated. The CeO2/Si photodetector fabricated at 63.66 J/cm2 showed the highest responsivity of 0.69 A/W at 450 nm, detectivity as high as 1.5 × 1010 Jones at 450 nm, and an external quantum efficiency of 92% when biased to 5 V. The photodynamic response time was measured. [ABSTRACT FROM AUTHOR]

Due to the remarkable progress in photovoltaic technology, enhancing efficiency and minimized the costs have emerged as global challenges for the solar industry. A crucial aspect of this advancement involves the creation of solar cell antireflection coating, which play a significant role in minimizing sunlight reflection on the cell surface. In this study, we report on the optimization of the characteristics of CeO2 films prepared by pulsed laser deposition through the variation of laser energy density. The deposited CeO2 nanostructure films have been used as an effective antireflection coating (ARC) and light-trapping morphology to improve the efficiency of silicon crystalline solar cell. The film's thickness increases as laser fluence increase. The refractive index of the antireflective film is measured as a function of laser fluence. The properties of CeO2 thin films' were characterized by various techniques. X-ray diffraction measurements show the grown films were crystalline with cubic and hexagonal phases. The degree of crystallinity of the film increases with the increase in the laser fluence. Scanning electron microscope results reveal that the film's morphology and film uniformity improved as the laser fluence increases. Raman shift of the CeO2 film as a function of laser energy density was investigated. Photovoltaic properties show that the conversion efficiency of the silicon solar cell increases from 8.37 to 14.04% after deposited with ARC CeO2 film at laser energy density of 76.39 J/cm2. The CeO2 films deposited at 76.39 J/cm2 laser pulse energy density have highest hydrophobicity among all the prepared samples. [ABSTRACT FROM AUTHOR]

Increasing the power conversion efficiency (PCE) of silicon solar cells by improving their junction properties or minimizing light reflection losses remains a major challenge. Extensive studies were carried out in order to develop an effective antireflection coating for monocrystalline solar cells. Here we report on the preparation of a nanostructured cerium oxide thin film by pulsed laser deposition (PLD) as an antireflection coating for silicon solar cell. The structural, optical, and electrical properties of a cerium oxide nanostructure film are investigated as a function of the number of laser pulses. The X-ray diffraction results reveal that the deposited cerium oxide films are crystalline in nature and have a cubic fluorite. The field emission scanning electron microscope investigations show an increase in the film grain size with increasing the number of laser pulses. The carrier concentration of the film decreases and the mobility increases as the number of laser pulses increases. The cerium oxide film deposited on silicon at 900 laser pulses exhibits a minimum optical reflection. The maximum PCE was 19.27% and fill factor of 87% was obtained after the deposition of silicon solar cell with cerium oxide nanostructured film deposited at 1000 laser pulses. [ABSTRACT FROM AUTHOR]

In this work, the effects of incorporating bare macroporous silicon (macro-Psi) layer with bimetallic nanoparticles Au-Ag on the performance Psi CO2 gas sensor synthesized by a laser-assisted etching (LAE) process were investigated. Well-controlled and simple immersion process of bare macro-Psi layer in the 10−3 M of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) individually and in the mixing solution with ratio 1:1 was employed to synthesize monometallic AuNPs/macro-Psi, AgNPs/macro-Psi, and bimetallic Au-AgNPs/macro-Psi hybrid structures of CO2 gas sensors. Morphological properties of bare macro-Psi layer, monometallic, and bimetallic hybrid structures were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and energy-dispersive X-ray analysis (EDS). Electrical characteristics (I–V)of the sensor were measured primary in a vacuum case and with CO2 at 0.2, 0.5, 1, and 1.5 mbar gas pressures. The result showed a significant enhancement in sensitivity and temporal response of the bimetallic hybrid structures compared with that of monometallic and bare macro-Psi layer and an enhanced performance of the sensors due to the high value of integrated specific surface area of the bimetallic nanoparticles and the resulting Schottky barrier height. [ABSTRACT FROM AUTHOR]

Two kinds of modified macro porous silicon (maPsi) layer with trimetallic nanoparticles surface alloying and core–shell forms CO2 gas sensors were fabricated and tested successfully. Trimetallic Au–Ag–Pd nanoparticles were prepared by an ion reduction process of different metallic salts on maPsi layer by a simple immersion process. As-formed maPsi layer was fabricated by a laser assisted etching (LAE) process with laser power density illumination, current density and etching time of about: 25 mW/cm2, 20 mA/cm2 and 20 min, respectively. Immersion process with different immersion times were carried out at a fixed concentration 1 mM of HAuCl4, AgNO3 and PdCl2 to synthesize Au–Ag–PdNPs/maPsi hybrid structures. Trimetallic core–shell nanoparticles form was prepared at (6, 8) min immersion times, while for surface alloying nanoparticles form was prepared at (2, 4) min immersion times in a mixed solution with a fixed ratio 1:1:1 at room temperature. The structural aspects of the as-formed maPsi layer and trimetallic Au–Ag–Pd nanoparticles were demonstrated by field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). The electrical properties of the modified maPsi layers with trimetallic nanoparticles with and without CO2 gas sensor were found at room temperature. A specific enhancement in gas sensitivity for trimetallic surface alloying nanoparticles form compared with that of the core–shell nanoparticles form was obtained due to the higher specific area to volume ratio. [ABSTRACT FROM AUTHOR]

Two NH3 gas sensor devices, Al/Si nanocolumns/n-Si/Al and Al/Ag NPs/Si nanocolumns/n-Si/Al hybrid structures, have been fabricated and tested. A bare silicon nanocolumns layer was synthesized by a laser-assisted electrochemical etching process in HF solutions. The surface morphology of bare Si nanocolumns was modified by incorporating Ag NPs into Si nanocolumns by simple and fast immersions methods in an aqueous solution of AgNO3 to synthesize a hybrid structure. Characteristic features of bare Si nanocolumns and hybrid structure were investigated using scanning electron microscopy, EDS analysis, FTIR spectra, X-ray diffraction, and photoluminescence spectra (PL). The electrical characteristics of sensors with and without NH3 gas were measured at room temperature. The results showed that the nanoparticles grain size, nature, specific surface area (S.S.A) of Ag NPs, and morphological structure of the Si nanocolumns strongly affected the property characteristics. A significant enhancement in sensitivity, response, and recovery times of gas sensor for a hybrid structure was realized after compared with Al/Si nanocolumns/n- Si/Al gas sensor due to the high specific surface area. [ABSTRACT FROM AUTHOR]

Monometallic nanoparticle Ag, Pd and bimetallic nanoparticles Ag@Pd with wellcontrolled morphology, uniform size, and regular alloy structure were produced by an ion reduction process with dangling bonds of porous layer Psi to fabricate monometallic(Ag, Pd) /macro Psi and bimetallic (Ag@Pd) /macro Psi hetro-structure. Psi substrate was synthesized by Photo-electrochemical etching (PECE) with a laser power density (15 mW/cm2), monometallic structure has been synthesized by dipping fresh Psi sample in salt solutions (AgNO3 and PdCl2) for about 5 min, while bimetallic nanoparticles was synthesized by dipping Psi in mix solution at a ratio (1:1) for about 2 and 4 min. The monometallic and bimetallic nanoparticles were confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). The results show that the composition of Ag@Pd alloy nanoparticles was uniformly dispersed and well-defined distribution on Psi surface; having an average size of (8 to 7.1) nm is smaller than monometallic nanoparticles sizes. The lower Ag@PdNPs size and therefore a higher specific surface area (S.S.A) were obtained for about (71 to 63.8) m2/gm, these high specific area is most important for different application such as: chemicals or gas sensing. [ABSTRACT FROM AUTHOR]