Applied Physics
Salah M. Abdul Aziz; Uday Muhsin Nayef; Mohammed Soham Rasheed
Abstract
Zinc oxide nanoparticles (ZnO NPs), copper oxide nanoparticles (CuO NPs) and CuO@ZnO NPs as a colloidal core-shell solution were synthesized by laser ablation. A Nd:YAG laser with an energy of 700 mJ, a wavelength of 1064 nm and 200 pulses was used for the ablation process. The colloidal solution was ...
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Zinc oxide nanoparticles (ZnO NPs), copper oxide nanoparticles (CuO NPs) and CuO@ZnO NPs as a colloidal core-shell solution were synthesized by laser ablation. A Nd:YAG laser with an energy of 700 mJ, a wavelength of 1064 nm and 200 pulses was used for the ablation process. The colloidal solution was deposited on porous silicon (PSi) using the drop-casting method. The PSi substrates were prepared by photoelectrochemical etching (PECE) on n-type (111) silicon wafers. The study investigated the influence on the electrical, optical, morphological and structural properties of the CuO NPs and ZnO NPs samples when they were converted into a core-shell, specifically for their use in photodetector applications. XRD analysis revealed the presence of CuO, ZnO and CuO@ZnO by diffraction peaks at different angles. According to the SEM images, the nanoparticles show randomly distributed spherical grains, while PSi exhibits a sponge-like structure. The core-shell shape is confirmed by TEM images, which show a dark inner region consisting of CuO NPs and a much lighter outer region consisting of the ZnO nanoshell. The optical properties of the CuO@ZnO NPs were investigated and a minimum energy gap of 2.8 eV was found. The CuO@ZnO NPs/PSi/n-Si photodetector showed improved current-voltage (J-V) characteristics, rectifying properties and remarkable sensitivity in the visible to near-infrared region compared to other photodetector samples. The fabricated photodetector confirmed improved quantum performance, especially in the visible spectrum. The work aims to synthesize CuO@ZnO core-shell nanoparticles by a laser ablation technique to improve the electrical properties and spectral response of photodetectors.
Laser Science and Technology
Raghad R. Mahdi; Marwa Kasim Abood
Abstract
In this study, cadmium oxide (CdO) was prepared by pulsed laser ablation in liquid (PLAL). The morphological structure and optical properties of the prepared CdO were determined by various analytical techniques, including SEM, AFM and XRD. The SEM images obtained showed that the prepared film exhibited ...
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In this study, cadmium oxide (CdO) was prepared by pulsed laser ablation in liquid (PLAL). The morphological structure and optical properties of the prepared CdO were determined by various analytical techniques, including SEM, AFM and XRD. The SEM images obtained showed that the prepared film exhibited cluster-like cubic structures. The AFM images showed a homogeneous and very uniform surface. In addition, XRD analysis revealed that the prepared film had a grain size of about 20 nm. The optical properties of the fabricated film showed an increase in absorbance values with a simultaneous increase in wavelength. The maximum value was measured at 340 nm, and the measured optical energy gap was about 2.55 electron volts (eV). The solar cell was produced by depositing a CdO film on the porous silicon. The fabricated solar cell achieved an efficiency of 0.16%. Therefore, the CdO film from this work could be an important factor for the development of gas sensors and solar cells. In addition, other powerful analytical techniques were performed in this study, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) observations.
Applied Physics
Yasamen H. Khadim; Uday M. Nayef; Falah A-H. Mutlak
Abstract
This study analyzes the effects of laser pulse energy set at 700 millijoules per pulse on silver, gold and silver@gold nanoparticles deposited on porous silicon (PS). Our main goal is to determine the optimal conditions by comprehensively evaluating their influence on structural, electrical, morphological ...
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This study analyzes the effects of laser pulse energy set at 700 millijoules per pulse on silver, gold and silver@gold nanoparticles deposited on porous silicon (PS). Our main goal is to determine the optimal conditions by comprehensively evaluating their influence on structural, electrical, morphological and optical properties. In pulsed laser ablation in liquid, a Nd:YAG laser with a pulse width of 10 nanoseconds and a wavelength of 1064 nm is used to produce the nanoparticles. X-ray diffraction (XRD) analysis confirms the crystalline growth of the core-shell nanoparticles with distinct peaks in the data confirming the presence of both Au and Ag nanoparticles. Morphological analysis shows a robust connection between the nanoparticles and the porous silicon layer, indicating structural stability. The UV–vis spectra show a localized surface plasmon resonance band (LSPR) in the range of 412–521 nm. It is noticeable that with increasing gold concentration the two peaks of the LSPR band converge to a single peak. Comparison of the photoluminescence emission spectra of the PS substrate and the NPs/PS shows a clear broadening of the emission band in PS, indicating a high-quality porous silicon structure. The intriguing properties of Ag@Au NPs make them promising for application in gas sensing systems.
Laser Science and Technology
Rasha B. Rashid; Alwan M. Alwan; Mohammed S. Mohammed
Abstract
In this work, an investigation was conducted to study the effect of electrodes’ configuration of the double morphology macPSi on the performance of electrically matched impedance pesticides sensors. The purpose was to develop an efficient electrical sensor for the quantitative detection process ...
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In this work, an investigation was conducted to study the effect of electrodes’ configuration of the double morphology macPSi on the performance of electrically matched impedance pesticides sensors. The purpose was to develop an efficient electrical sensor for the quantitative detection process of (Chlorpyrifos) pesticide in organic solvents. The effect of electrodes configuration of the front, front-back, and back coplanar electrodes on macPSi as based substrate was tested to select an optimum sensor metallization pathway. The based efficient macPSi layer was fabricated using elevated laser irradiation power density at different periods. Morphological, optical, and electrical properties of the sensors were investigated using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, and R-L-C measurement. The sensing method depended on measuring the resonance frequency shift as the organic solvent was exposed to the sensor’s surface. The sensor’s performance at various configurations and concentrations ppm was inspected at room temperature. The current findings revealed extremely low instabilities (less than 0.017 %), higher sensitivity, and a detection limit of 0.004ppm for top coplanar electrode configuration. The fabricated sensor is simple and low-cost for excellent quantitative pesticide detection.
Laser Science and Technology
Ahmed Z. Abdullah; Adawiya J. Haider; Allaa A. Jabbaar
Abstract
Manufacture of an environmental polluting gas sensor with improved properties by controlling the preparation conditions of the photo-electrochemical etching technique (PECE). The amount of porosity, the diameter of the pores, and the thickness of the prepared layer of porous silicon (Psi) can be controlled ...
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Manufacture of an environmental polluting gas sensor with improved properties by controlling the preparation conditions of the photo-electrochemical etching technique (PECE). The amount of porosity, the diameter of the pores, and the thickness of the prepared layer of porous silicon (Psi) can be controlled by changing one or all of these conditions. In this paper, n-type Si with a crystalline orientation (100) was used, whereby PSi was prepared with the use of a red diode laser with a wavelength of 650 nm, using different radiation intensity, and with the constancy of etching time and current density. Through the results obtained, it was noted that: the porosity increases significantly up to 75% as well as the thickness of the PSi layer up to 1.45 µm with the increase in the intensity of the laser beam. Also, examining the morphology of the surface samples by field emission scanning electron microscope (FE-SEM) besides, the average pore diameters of the prepared samples were calculated. It is clear that the intensity of the laser beam used in the irradiation process is one of the important factors in determining the properties of the prepared PSi. PSi samples have been tested by FTIR to investigate chemical bonds on surfaces such as, (Si-Si, Si-H, Si-H2, Si-O-Si, Si-O-Si, Si-H, Si-O-Si). Samples tested as gas sensors and noticed that an increase in the sensing current to 5.3 µA has appeared with the increase of porosity value where methanol gas is used as background.
Applied Physics
Eman M. Suliman; Uday M. Nayef; Falah A. Mutlak
Abstract
In this study, Au:TiO2 nanoparticles (NPs) are prepared by using the laser ablation method in liquid at different laser energies (600, 800, and1000 mJ). After that, Au: TiO2 NPs were deposited on porous-Si(PS). Porous silicon (PS) is synthesized by using the photo-electrochemical etching (PECE) of n-type ...
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In this study, Au:TiO2 nanoparticles (NPs) are prepared by using the laser ablation method in liquid at different laser energies (600, 800, and1000 mJ). After that, Au: TiO2 NPs were deposited on porous-Si(PS). Porous silicon (PS) is synthesized by using the photo-electrochemical etching (PECE) of n-type crystalline Si (c-Si) wafers of (100) orientation. The intensity of the etching current density was (4, 12, and 20 mA/cm2), with 16% (HF), and the etching time was 15 minutes. The X-ray diffraction (XRD) techniques, scanning electron microscopy (SEM), UV–visible spectrophotometry, and electrical properties are used to characterize the obtained particles. From the photo-detector measurements, the spectral responsivity curves three inclusive regions; the first peak was due to the absorption of UV light by Au: TiO2 NPs. The second peak was corresponding to the visible light absorption with the PS layer and the third peak was due to the absorption edge of the Si substrate. The higher responsivity of Au: TiO2 NPs/PS photo-detector was found to be 2.56A/W for specimens prepared at laser energy 800mJ.
Laser Science and Technology
Suha G. Ali; Mohammed S. Mohammed; Fatima I. Sultan
Abstract
The present work is a study of some properties of PbI2 deposited on porous silicon (n-PSi) by using the thermal evaporation technique. X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometer, and FTIR analysis were used to characterize the structural, optical, and morphological ...
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The present work is a study of some properties of PbI2 deposited on porous silicon (n-PSi) by using the thermal evaporation technique. X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometer, and FTIR analysis were used to characterize the structural, optical, and morphological properties of n-Psi. X-ray diffraction showed that the PbI2 film has a hexagonal polycrystalline structure, while FE-SEM images showed porous silicone in Photoelectrochemical etching, the pore distribution is irregular and the pore refers to the increased surface area of the silicon. SEM images of pbI2 film showed that particles were scattered and resembled gravel in size. The estimated optical energy value of thin films of PbI2 was 2.6 eV. PbI2 film has lower transmittance values at short wavelengths, but as the wavelength increases, the transmittance values gradually increased. The greatest transmittance value was 0.88. From FTIR analysis, chemical bonds were determined between porous silicon and PbI2.
Nanotechnology
Shahad S. Khudiar; Uday M. Nayef; Falah A. Mutlak
Abstract
Photoelectrochemical etching (PECE) was used to prepare porous silicon (PS) layers of polished surfaces of (100) n-type silicon wafers with a resistance of 0.1-100 μm and thickness of 600 ± 25 μm. The directed slices are to be catalyzed at different etching times (5, 15, 25 min) with a constant ...
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Photoelectrochemical etching (PECE) was used to prepare porous silicon (PS) layers of polished surfaces of (100) n-type silicon wafers with a resistance of 0.1-100 μm and thickness of 600 ± 25 μm. The directed slices are to be catalyzed at different etching times (5, 15, 25 min) with a constant Hydrofluoric acid of 20% and with a fixed current density of 20 mA/cm². The porous silicon morphology was investigated using scanning electron microscopy (SEM). Samples were formed by different engraving times. It revealed that the silicon surface has a layer of sponge-like structure, with the average pore diameter (740±1 nm, 550±2 nm,460±3 nm) of the porous silicon increasing as the etching time increased. PS Al PS /Si /Al photodetectors were found to work as a photodetector over a wide wavelength responsivity.
Laser Science and Technology
Noor S. Dawood; Mehdi Q. Zayer; Muslim F. Jawad
Abstract
The manufacturing of vacuum sensors is critical to several vacuum-based applications. Porous silicon (PSi) was chosen as the vacuum sensor due to the possibility of moving air particles settled inside the pores while being put in the vacuum. The characteristics of porous silicon sensing to the evacuation ...
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The manufacturing of vacuum sensors is critical to several vacuum-based applications. Porous silicon (PSi) was chosen as the vacuum sensor due to the possibility of moving air particles settled inside the pores while being put in the vacuum. The characteristics of porous silicon sensing to the evacuation of gases during vacuum was inferred by changing in the electrical resistivity. This work depends on the change in the electrical resistance of the PSi layers that was prepared via photo-electrochemical technique on the n-type (100) oriented silicon wafer. The surface topography of porous silicon is necessary to understand the morphological properties. Therefore, structural and morphological characterization of PSi samples were studied and analyzed using the scanning electron microscope (SEM) and X-Ray Diffraction (XRD) pattern. The etching process was carried out with various etching times, hydrofluoric acid (HF) concentration, and constant current density. The results showed that the pore size is increased as the etching time increased. The etching time produced pores of different sizes. The electrical resistance values were calculated after placing the sample in the vacuum system, starting from atmospheric pressure down to torr. The electrical properties of PSi indicate that electrical resistance gradually decreases with increasing vacuum pressure.
