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Abstract In this work, ultra-sensors of chemical solvents vapor were fabricated for chloroform, n-Hexane and Ethanol via modified porous silicon (PS) surface by the reduction of graphene oxide (rGO) layer. The rGO was conducted by electrochemical exfoliation of graphite electrodes with electrolyte solution at PH = 4.6. Then porous silicon (PS) was prepared by employing electrochemical etching (ECE) method using silicon (Si) p-type at different etching current density J = 2, 4 and 6 mA/cm2with constant HF concentration of 15%, and time of etching of 15 min. The reduction graphene oxide competition with PS was studied as vapors organic sensor, morphological, structural, and surface bond configuration were characterized by Atomic Force Microscopic (AFM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) respectively, then the Photoluminescence (PL) quenching was measured by using sensor test system with three types of organic chemical solvents n-Hexane, chloroform and ethanol with nitrogen gas mixing, where they were prepared for testing humidity sensor towards the different organic solvents. The results revealed that the reduction graphene oxide layer on surface of PS lead to intensity increase of the PL, and modified the quality of PS sensor for chemical vapor. [ABSTRACT FROM AUTHOR]

Abstract Porous silicon (PS) has attracted considerable attention as potential materials for gas/vapor sensing because of very high surface to volume ratio. PS with some metals such as Co 3 O 4 is necessary to create and provide new nanocomposite materials with new properties that combine semiconducting and magnetic properties. In the present work, the samples to be studied were characterized from atomic force microscope (AFM), X-ray diffraction (XRD), reflectivity, photoluminescence (PL) spectra and humidity sensor. X-ray diffraction for PS in the range of 20°-70° at 2 theta, show an important peak at 28.35◦ oriented (111), while the Co 3 O 4 /PS have four characteristic peaks at 36.758°, 44.738°, 59.177° and 64.980°, were corresponding to the oriented (311), (222), (511) and (440) respectively. PL test for PS/Co 3 O 4 shows a slightly less intensity and slight change in location in case of PS due to Co 3 O 4 NPs granular size which acts as a cover, thus reducing the surface area of the PS which reduces PL. In PS/Co 3 O 4 sample shows that the PL spectra peak is different from PS at shape and the effect of relative humidity (RH) at this peak due to the decrease of intensity at peak. Through these results we conclude that PS/Co 3 O 4 can be used as sensor humidity. [ABSTRACT FROM AUTHOR]

In this work chemical vapor sensors for Ethanol, chloroform and n -Hexane were fabricated by porous silicon (PS). PS samples were prepared by electrochemical etching (ECE) method with different current density J = 2, 4 and 6 mA/cm 2 and etching time 15 min and HF concentration 15%. Ordered porous silicon p-type (111) is thoroughly studied as an The structure, chemical composition and surface bond configuration of PS layer has been characterized by X-ray diffraction (XRD), Atomic Force Microscopic (AFM) and a Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence (PL) quenching measurement were conducted using mixture nitrogen gas and vapor of n -Hexane, chloroform and ethanol, where prepared to test the sensor response towards the chemical organic solvents. The results refer to the PS surface is good sensing for chemical vapor. It's were also found that a higher PL quenching value for Ethanol compared with the value of n -Hexane and chloroform vapors. [ABSTRACT FROM AUTHOR]

ZnO nanostructures have lately been deemed an effective material for fabricating gas sensors, As a result, ZnO nanoparticles are commonly utilized to make effective gas sensors for detecting a variety of hazardous and poisonous chemicals. The current review article focuses on nitrogen dioxide (NO 2) gas sensor advances based on ZnO nanoparticles, X-ray diffraction confirmed the wurtzite structure, Surface roughness, layer homogeneity, and morphological structural analysis are studied using Atomic Force Microscopy (AFM). UV–vis and photoluminescence spectra were used to study the optical characteristics of the as-prepared ZnO nanostructures, The electrical properties such as the current density-voltage (J-V) measurements, Finally, the effects of adjusting operating temperature of NO 2 gas sensor made from the prepared samples on sensor's sensitivity, recovery time and response time have been explored. [ABSTRACT FROM AUTHOR]

In this study, prepared Au:ZnO core-shell nanoparticles (CSNPs) by pulse laser ablation in liquid (PLAL), and succeed to control of growth the ZnO NPs and play a role as a shell decorated on surface of Au NPs as a core. The structure, morphology and visual qualities were examined. The XRD result explained the phase of ZnO NPs was wurtzite structure, and for Au NPs as a cubic crystal. The morphology of structures illuminates the agglomerated and adherent ZnO NPs on Au NPs. TEM image is clearly show the spherical particles for Au NPs with mean size 12 ± 1 nm, and the mean size for ZnO NPs is 29 ± 2 nm, while, its clearly show increased for size of Au:ZnO CSNPs to 45 ± 2 nm. [ABSTRACT FROM AUTHOR]

In the present work, the characterization and preparation of the ZnO nano-particles (ZnO NPs) through the laser ablation in the methanol at a variety of the laser energies 400, 600 and 800 mJ, XRD analysis When the crystal size is inside a nanometer, shows a large diffraction peak, by Atomic Force Microscopic (AFM) study the surface roughness and layer homogeneity and Morphological structural, Photoluminescence (PL) test. Finally, the effect of changing the operating temperature of the gas sensors of NO 2 that have been produced from prepared samples on the sensitivity of the sensor, response time, and recovery time was investigated, with the highest sensitivity for ZnO NPs/PS, ablated with laser energy of 600 mJ on porous silicon. [ABSTRACT FROM AUTHOR]

In this study, synthesis and characterizing of Gold:Zinc Oxide (Au:ZnO) as a core:shell nanoparticles (CSNPs) has been prepared via Laser Ablation at various Laser Pulses Energy 400, 600, and 800 mJ with 200 strokes. Further confirmation of the production of Au:ZnO CSNPs by analyzing the structural and optical properties from aggregated Au:ZnO. CSNPs obtained via drop casting Au:ZnO CSNPs colloidal solutions into silicon wafers. Nanoparticles were identified via X-ray diffraction, transmission electron microscopy, Fourier transform infrared, and ultraviolet–visible absorption spectrum. It was found particle size increased with energy, and the shell of ZnO on the surface of gold nanoparticles is strongly affected on absorptions, while the absorption of Au:ZnO CSNPs decreased when the decorated surface of Au by ZnO corresponding to Au and ZnO as an individual. [ABSTRACT FROM AUTHOR]

In the present study, synthesis and characterization of Zinc Oxide (ZnO) nano-particles with the pulsed laser ablation (PLD), from a zinc metal target in methanol at a variety of the laser pulse energy values 400, 600 and 800 mJ with 200 shots and 1064 nm laser wavelength. Porous silicon (PS) layers were prepared from n-type silicon with orientation (100) by photo-electrochemical etching (PECE) method. The morphological properties of ZnO NPs deposited on PS presented a good adhesion between these nanostructures leading to improve the structural stability of the PS substrate. UV–vis–NIR spectrophotometer, X-ray diffraction (XRD), electrical characteristics and Photodetector are utilized for the characterization of the products. So the detector measurements of ZnO NPs/PS exhibited a higher responsivity (0.04 A/W). [ABSTRACT FROM AUTHOR]

The presented study synthesized C:Se NPs via a combination of the laser along with magnetic field at various laser pulse energies 200, 600 and 1000mJ with 100 shots, have been deposited on the porous silicon (PS) through the use of drop-casting method. The pattern of the X-ray diffraction (XRD) had indicated the nanocrystaline of specimens. In Atomic force microscopy (AFM), which shows agglomeration of C:Se NPs increased, the distribution of the granularity showed that the distribution of part was almost Gaussian, also the transmission electron microscope (TEM) indicated that the synthesized C:Se particles have an average particle size of 35 nm. Bright-field TEM images show complementary contrast, confirming the formation of core/shell structures. The optical measurements in wavelength range ultraviolet-visible near infrared (UV–vis–NIR) as well as a transition of indirect type with 4 eV band gap is specified. Also, the electrical characteristics like barrier height (Φ B), ideal factor (n) for Al/C:Se NPs/PS/Si/Al heterojunction were concluded with measurements of current-voltage (I-V). Lastly, the operation temperature variations associated with NO 2 and NH 3 gas sensors are subjected to fabrication from the prepared samples on response time, sensor sensitivity and recover time was examined. The maximum sensitivity of C:Se/PS at 1000 mJ gas sensor to 60 ppm of NO 2 about 202.5% at around 100 °C,also the maximum sensitivity of C:Se/PS at 1000mJgas sensor to 200 ppm of NH 3 can reach 17.9%, and the optimum sensing temperature of C: Se/PS sensor is at around 150 °C. [ABSTRACT FROM AUTHOR]

In this work, synthesis and characterizing of carbon: selenium nanoparticles (C:Se NPs) are synthesized by laser ablation Q-switched Nd:YAG laser with wavelength of 1064 nm at different laser pulses energy 200, 600 and 800 mJ with 100 shots and porous silicon (PS) was presented. X-ray diffraction (XRD) was utilized for examining the structural properties. In addition, the results of the Atomic force microscope (AFM) analysis an 39.76 nm as average diameter which is coordinated in rod-like shape appearing for C:Se NPs, also the transmission electron microscope (TEM) indicated that the synthesized C:Se particles have been spherical with average particle size in range of (25 and 75) nm. Lastly, the variations of operation temperature related toNH 3 and NO 2 gas sensors that are fabricated from prepared samples on the sensor sensitivity, recover time and response time were examined, the maximum sensitivity is approximately 205% with regard to (C:Se NPs) ablated via laser energy 800 mJ on PS of gas NO 2 , also the maximum sensitivity is approximately 43% in terms of(C:Se NPs) ablated via laser energy 200 mJ on PS of gas NH 3. [ABSTRACT FROM AUTHOR]

In this work, Carbon:Selenium (C:Se) nanoparticles (NPs) are preparation by laser ablation at diverse laser energy 200, 400, 600,800 and 1000 mJ with 100 shots and laser wavelength 1064 nm then deposited on porous silicon (PS). PS are fabricated using electrochemical etching (ECE) method for p-type crystalline silicon (c-Si) wafers of (100) orientation.The pattern of X-ray diffraction (XRD) showed the sample's nanocrystaline.Results of the Atomic force microscope (AFM) analysis an average diameter of 39.76 nm coordinated in a rod-like shape appears for C:Se NPs. UV–vis result displayed that the optical energy gap of the nanoparticles increases. The electrical properties such as barrier height (Φ B) and ideality factor (n) of the Al/C:SeNPs/PS/Si/Al heterojunction were determined from the current density-voltage (J-V) measurements. [ABSTRACT FROM AUTHOR]

In this research, C:Se (core:shell) nanoparticles(NPs) are laser ablated at various laser energies of 200, 400, 600, 800 and 1000 mJ with 100shots and 1064 nm laser wavelength then deposited on porous silicon (PS). The XRD study showed that C:Se NPs are crystalline and belong to the monoclinic symmetry α-phase. Results of the AFM (i.e. atomic force microscope) analysis for PS has shown sponge-like structure, and a 39.76 nm average diameter coordinated in a rod-like shape appearing for C:Se NPs, are watched and electrical characteristics are studied to identify samples. From current-voltage (I-V) measures, the electrical characteristics, like height of the barrier (Φ B) and ideality factor (n) of Al/PS/Si/Al and Al/C:Se NPs/PS/Si/Al heterojunction have been determined. Finally, a wide variety of wavelengths has increased the efficacy of C:Se NPs/PS photodetectors. [ABSTRACT FROM AUTHOR]

Magnesium Oxide nanoparticles (MgO NPs) ablated on porous silicon (PS) substrate using Laser pulse ablation technique with different preparation conditions. The preparation samples offer sponge-like structure of PS and crystalline MgONPs structure with a bright spot inside PS. MgO NPs/PS perform improvement in the photoconversion efficiency properties, that are represented as decrease reflectivity, and enhancement in both of the responsivity and quantum efficiency. Therefore, MgONPs/PS can be used as a photodetector operated over broadband spectral of wavelength. [ABSTRACT FROM AUTHOR]

In this work, preparation and characterization of Bi 2 O 3 nanoparticles (Bi 2 O 3 NPs) by laser ablation in liquid at various laser energy 200, 400, 600 and 800 mJ. X-ray diffraction (XRD) investigation is appeared broad diffraction peak when the size of the crystal becomes inside nanometer. Scanning electron Microscopy (SEM) study results for porous silicon (PS) showed sponge like structure and Bi 2 O 3 NPs nanoparticles appear as bright spots. Observed the reflectivity of Bi 2 O 3 NPs on PS is less than Si bulk and PS, however. From Raman result show peaks at 81 cm−1 and 303 cm−1, are the specific bands of α -Bi 2 O 3. The band at 303 cm−1, are assumed to be because of Bi–O stretches. The electrical properties such as barrier height (Φ B) and ideality factor (n) of the Al/Bi 2 O 3 NPs/PS/Si/Al heterojunction were determined from the current–voltage (I-V) measurements. Finally, the variation of operation temperature of NO 2 gas sensors which fabricated from the prepared samples on sensor sensitivity, response time and recover time have been studied, and the maximum sensitivity was about 71 % for Bi 2 O 3 NPs ablated by laser energy 600 mJ on PS. [ABSTRACT FROM AUTHOR]

In this work, bismuth oxide nanoparticles (Bi 2 O 3 NPs) are preparation by laser ablation at diverse laser energy 200, 400, 600 and 800 mJ with 100 shots and laser wavelength 1064 nm then deposited on porous silicon (PS). X-ray diffraction (XRD) study revealed that Bi 2 O 3 NPs is crystalline and belong to α-phase with monoclinic symmetry. Atomic force microscope (AFM) study results for PS showed sponge like structure, and for Bi 2 O 3 NPs appears an average diameter of 31.09 nm coordinated in a rod-like shape, are watching and electrical properties are carried out to describe the samples. Fourier Transform Infrared (FTIR) spectra showed the oxidation of PS substrate resulting in the passivating of the surface states and for Bi 2 O 3 NPs/PS confirming the presence of Bi-O bond. The electrical properties such as barrier height (Φ B) and ideal factor (n) of the Al/PS/Si/Al and Al/Bi 2 O 3 NPs/PS/Si/Al heterojunction were calculated from the current–voltage (I-V) measurements. Finally, we appeared enhanced effectiveness of Bi 2 O 3 NPs/PS photodetectors through a wide domain of wavelengths. [ABSTRACT FROM AUTHOR]

In this research, the nanoparticles of gold (AuNPs) was used for doping graphene (rGO) nanocomposites, then deposted on porous silicon (PS) for high sensitivity of chemical vapors sensor such as n -Hexane, Ethanol, and chloroform. The graphite electrodes were used for the production of rGO by electrochemical exfoliation method. The pulsed Nd:YAG laser system with 1064 nm of wavelength, and laser energy of 400 mJ for 600 pulses was used for AuNPs preparation. Then the electrochemical etching (ECE) system was used for prepared PS with the variation of etching current densities: 2, 4 and 6 mA/cm2 for 15 min etching time. The comparison of rGO:AuNPs/PS with PS surface was studied for a chemical vapors sensor. The X-ray diffraction (XRD), Atomic Force Microscopic (AFM), Scannin electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were performed for studying the Structural, morphological and surface bond configuration respectively and the UV–vis spectrophotometer applied for calculating transmittance ratio of hybrid materials. The Photoluminescence (PL) test was conducted for all samples using PL system on the three kinds of organic chemical solvents, by mixing with gas of nitrogen, in which prepared for using as the sensor of organic vapors. All results showed that the hybrid doping of rGO:AuNPs layers on the PS surface lead to rise of PL peak, and modify the PS feature as organic chemical vapor sensor. [ABSTRACT FROM AUTHOR]

The hydro-thermal ZnO nanostructure synthesis is described in this paper. ZnO nanoparticles have been studied with the use of a scanning electron microscope (SEM), and X-ray diffraction (XRD) confirmed the formation of ZnO's hexagonal structure of the wurtzite. The produced nanostructure's average crystallite size was 21 nm. From UV–Vis absorption spectra, the bandgap of ZnO nanostructures was estimated, and the bandgap was 3.0 eV for ZnO. The porous silicon (PS) layers have been made from n-type silicon (100) orientation using the photo-electrochemical etching (PECE) process. Electrical attributes and a photodetector are utilized to characterize the product. The findings indicate that such hydrothermal synthetic method may produce high-quality ZnO nanoparticles. The photo-conversion characteristics of ZnO NPs/PS are improved, resulting in an increase in the responsivity. As a result, ZnO NPs/PS might be employed as a photodetector with a broad wavelength spectral range. [ABSTRACT FROM AUTHOR]

The effectiveness of applying an external magnetic field in the C:Se/PS was studied nanoparticle (NPs) synthesized in a laser wavelength generated by a Q-switched- laser via pulsed Laser Ablation in 1064 nm. The pattern of the X-ray diffraction (XRD) had indicated the nano-crystaline of specimens. Results of the Atomic force microscope (AFM) analysis for C:Se/PS showed have decreased the average roughness after magnetic field application. UV–vis result displayed that the gap of the optical energy of nano-particles increase from 3.6 to 4.2 eV following the application of magnetic field throughout ablation. The electrical characteristics like the ideal factor (n) and barrier height (Φ B) for Al/C:SeNPs/PS/Si/Al heterojunction have been determined with measurements of current-voltage (I-V). In addition, the effectiveness of C:Se/PS photodetectors was improved across a wide range of wavelengths, the quantum efficiency (Q.E) of C:Se/PS photodetectors decreased from 85% to 23% at 600 nm following the application of magnetic field throughout ablation. [ABSTRACT FROM AUTHOR]

This work aim to achieving laser nano-textured Si structures by means of an ultra-fast ultra-violet femtosecond (fs) laser texturing technique. The evidences of the impact of the duration of irradiation of the femtosecond laser pulses on Silicon (Si) have been investigated experimentally. A Ti:Sapphire laser at 800 nm (130 fs pulse duration with 1 kHz rate of repetition) has been employed to create nano-textured surfaces in an n-type (111) Si wafer of 0.015 Ω.cm resistivity and 508 ± 5 μm thickness. The average sizes of diameters were estimated to be in the 25−45 nm. From PL measurements of Si nanostructures, size dependent shifts in the direction of the blue spectral region have been emphasized. A highly symmetrical band shape was recognized from the samples' Raman spectra after the irradiation, the phonon frequency (phonon peak shift) shifted below 520 cm−1. The surface nanostructured Si showed lower reflectance values compared with bulk Si (un-irradiated). The observed enhancement of the fabricated Si nanostructures broad spectral response, which is in the range between the visible to the near infrared (NIR) 400−1150 nm, was attributed to increasing light absorption within sub-nanostructures. Thus, the proposed technique could be a promising approach to enhance the performance of Si-based photo-detector. [ABSTRACT FROM AUTHOR]

Porous silicon (PS) prepared from n-type silicon via photoelectrochemical etching (PECE) technique. The morphology properties of PS specimens that formed with different etching time has been study utilize Scanning electron microscopy (SEM) and it show that the Layer of pore has sponge like stricture and the average pore diameter of PS layer rising with increase etching time. The X-ray diffraction (XRD) pattern indicated the nanocrystaline of the specimens, during these results; we showed improve behavior of PS photodetectors on a range of wavelengths. [ABSTRACT FROM AUTHOR]

Humidity is the one of physical quantities that widely measured and is of very important in a many fields. In this paper, the ultra sensor of humidity was created using modified porous layer of silicon (PS), by thin films of reduction graphene oxide sheets (rGO). The electrochemical method was applied to exfoliation electrodes of graphite for preparing rGO sheets in peeling solution Acidic about PH = 4.6. p-type of Silicon waver (Si) was used for formulating PS samples using electrochemical etching (ECE) process. three etching current density 2, 4 & 6 mA/cm2 were used and fixed the other parameters such as Hydrofluoric acid HF c concentration was 15%, and time of etching about 15 min. All the samples of PS and rGO/PS were tested as humidity sensor. the structure characteristic, morphological properties and surface chemical bonds configuration were described by X-ray diffraction (XRD)و Scanning electron microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) consequently, also the Photoluminescence (PL) tests were conducted by using system of sensor test, the measurements of PL in a controlled humidity atmosphere (mixing gas of Nitrogen with humidity (vapor of water) were performed for examining the sensor response to the water vapor. The results showed that all samples revealed that the PL intensities were increased while rGO sheets deposited on the surface layer of PS, and improved the sensitivity of PS as humidity sensor. [ABSTRACT FROM AUTHOR]

In this paper, synthesis and characterizing of bismuth oxide nanoparticles (Bi 2 O 3 NPs) are synthesized by laser ablation at different laser pulses energy 200, 400, 600 and 800 mJ with 100 shots and laser wavelength 1064 nm and porous silicon (PS) was presented. Scanning electron Microscopy (SEM), x-ray diffraction (XRD), UV–vis-NIR spectrophotometer and electrical properties are used to characterize the products. The results show X- ray patterns analysis and improve the crystalline structure of Bi 2 O 3 nanoparticles which relate to α- phase and monoclinic symmetry. SEM image shows approximate spherical particles with a little agglomeration for both samples. From results transmittance of Bi 2 O 3 NPs suspension with energy bandgaps ranging from the infrared up to near-ultraviolet can be obtained, depending on their structure and morphology. Based on these results, we demonstrated enhanced performance of Bi 2 O 3 NPs/PS photoddetectors over a broad range of wavelengths. [ABSTRACT FROM AUTHOR]

The silver oxide (Ag 2 O) nanoparticles thin films were deposited on the glass, silicon (Si), also porous silicon (PS) substrates which are kept at room temperatures using pulsed laser deposited (PLD) technique. The optical band gap related to thin films has been 2.05 eV. Also, the XRD researches specified that thin films have polycrystalline cubic phase. Prepared thin films were used in gas sensors applications. The thin film show that the sensitivity increased with increased operation temperature, the Ag 2 O/PS has sensitivity more than Ag 2 O/Si. Recovery time and response time are increased with the increase in the operating temperature which is related to Ag 2 O/Si, whereas the recovery time and response time are reduced with increasing in operating temperature of Ag 2 O/Si. [ABSTRACT FROM AUTHOR]