Morphology Of Silicon Research Articles

Reflection Prediction of Black Silicon Texture Under the Guidance of Image Recognition Technology

Black silicon texturing has been considered to be a promising wafer texturing technology and can effectively improve the short-circuit current and, thus, power conversion efficiency, which has been widely used in the multicrystalline silicon photovoltaic industry. In this article, we propose a new method to “recognize” the black silicon morphology from the scanning electron microscope (SEM) images and to predict the resultant reflectance. ImageJ software was applied to recognize and analyze the SEM images for the first time, to obtain the acid-etched pit parameters. Then, we applied the recognized parameters into the sigmoid-Boltzmann equation to obtain an accurate distribution of the pit size. Finally, a modified model has been established to describe the exponential relations between the reflectance and the ratio of pit depth d over wavelength λ (d/λ), pit size, and pit coverage proportion. For the typical pit size 500-800 nm in mass production, its depth is about half of the wavelength λ. Thus, we can predict the reflectance of the black silicon surface precisely, by monitoring their SEM images. The average reflectance deviation between the measured and the predicted reflectance is ~3.7% relatively.

Effect of Different Phosphorus Modifiers on Microstructure and Properties for Al-Si Alloy

The coarse primary silicon structure will deteriorate the material properties of Al-Si alloy. It is necessary to optimize the morphology and size of primary silicon through modification, so as to improve the properties of Al-Si alloy. In this paper, four different phosphorus modifiers, AlP4, P-salt, P-Cu and Al-3P, were used to modify the Al-Si alloy. The microstructure and mechanical properties of the modified Al-Si alloy were compared and analyzed.

The Effects of Psi Morphology on the Detection Efficiency of the Au-Nps Hot Spot SERS Sensors

This work is related to the investigation of the effects of porous silicon (PSi) morphologies on the performance of plasmonic gold nanoparticles (Au-NPs) hot spot SERS sensors for the detection of amoxicillin molecules. Two Si wafers with different resistivity values of 10 and 100 Ω.cm were used to synthesize a PSi layer of pores- and mud-like structures, respectively, by pulsed photo chemical etching process. The hot spot SERS sensors were synthesized by incorporating the Au-NPs within the PSi morphologies of pores- and mud- like structures which are characterized by high density of nucleation sites. Plasmonic Au- NPs with different sizes and hot spot regions were incorporated into the porous structures by the ion reduction process. It was recognized that the PSi morphologies have a considerable influence on the fabrication process of the detection sensors and, consequently, on the detection process. The plasmonic Au-NPs hot spot SERS sensor based on the PSi morphology of the mud-like structures shows higher sensitivity than that of pores-like structures, even at very low concentrations of amoxicillin solutions.

The effect of the acid concentration on morphology of nano crystalline silicon

In the present work the effect of the different concentrations of HF:ethanol (1:1, 1:2, 1:3, 1:4, 1:5) on the properties of porous silicon was studied by using porous silicon prepared from n-type and p-type bulk silicon of resistivity (1–10 Ω.cm) and HF (39–43%) and ethanol (99%) in 10 min and 10 V with electro-chemical etching for p-type and photo electro chemical etching for n-type. Furthermore, the layer thickness and porosity were studied by using graph metric method and SEM for porous silicon from n-type and p-type.

Hot compression and industrial extrusion characteristics of an as-cast Al-10Sr master alloy

Abstract The mechanical properties and castability of Al-Si-based alloys can be remarkably improved by adding Al-Sr master alloy, which modifies the structure and morphology of eutectic silicon. The size of Al4Sr phases in Al-Sr master alloy has been found to take key effect in Sr-modification. To obtain optimized processing parameters and understand the refinement mechanisms of Al4Sr phases during plastic deformation, the hot compression and industrial extrusion characteristics of an as-cast Al-10Sr master alloy were systematically investigated in this work. The results showed that the flow behavior of the Al-10Sr master alloy can be well described by a constitutive equation with the hot deformation activation energy of 222.23 kJ/mol. The obtained optimum processing region was located at temperature of 460–530 °C and strain rate of 0.2–1 s−1 from the established processing maps. During hot compression testing, plastic deformation mainly occurred in soft Al matrix and the Al4Sr phases were slightly broken. During industrial extrusion process, the Al4Sr phases were refined effectively based on the above optimum processing conditions. Comparing to conventional extrusion process, repetitive Conform process showed better ability in refining Al4Sr phases. After three repetitive Conform passes, the length of Al4Sr phases decreased from 80 to 11 μm and the width decreased from 25.6 to 8.3 μm, and the Al4Sr phases were also distributed homogeneously. The in-depth refinement mechanisms of Al4Sr phases during plastic forming were also discussed based on microstructural examinations and finite element analysis.

Effect of Modification with Different Contents of Sb and Sr on the Thermal Conductivity of Hypoeutectic Al-Si Alloy

In this paper, the effects of size, morphology and distribution of eutectic silicon on the thermal conductivity of Al-8Si alloy modified by Sr (0.04, 0.08, 0.12 wt.%) and Sb (0.1, 0.3, 0.5 wt.%) elements with T6 heat treatment were investigated. The results show that the modified fibrous eutectic silicon has a significant capability of improvement of thermal conductivity, while the amount of the modifier has a relatively weak effect on thermal conductivity. After T6 treatment, the fracture or spheroidization of the flake eutectic silicon and the disappearance of clustering phenomenon could raise thermal conductivity, but the coarsening of fibrous eutectic silicon is inconducive to thermal conductivity. Finally, the effect of eutectic silicon on electron transport is analyzed in detail, which could provide a reference for enhancing the thermal (or electrical) conductivity of hypoeutectic Al-Si alloy through effective microstructure control.

Nanoscale zero-valent iron supported by attapulgite produced at different acid modification: Synthesis mechanism and the role of silicon on Cr(VI) removal

The attapulgite of different morphologies and mineral compositions were successfully obtained following the treatment by HCl and HF with different concentrations. Variations of morphologies, elemental and mineral components of the pristine and modified attapulgite were investigated and assessed in detail by a series of characterization methods. The SEM-EDS results indicated significant variations on the contents and morphologies of silicon after acid modification. The Cr(VI) removal efficiencies under pristine and modified attapulgite-supported nZVI composites were evaluated with the removal rate in case of 0.5HAT-nZVI being 69.2% more superior than that of 6FAT-nZVI. The reaction kinetic is well fitted with pseudo second order kinetics model. The correlation analysis indicated that Cr(VI) removal efficiency was positively correlated with the content of active silicon in the attapulgite-nZVI composites (R2 = 0.979∗∗). Additionally, the reduction of Cr(VI) is more likely to occur in silicon-rich composites based on the analysis of XPS spectra and Cr concentration changes, which were mainly attributed to the enhanced Si–O–Fe coupling mediated by silicon. Attapulgite with more exposure sites of silicon enhanced the Cr(VI) reduction process and promoted crystallization of the reaction products. Simultaneously, the nZVI consumption caused by oxidation and aggregation were improved by silicon in attapulgite. It is concluded that silicon played a significant role on Cr(VI) removal through the reductive precipitation by Si–O–Fe coupling.

Simultaneously improving strength and ductility of hybrid Al–Si matrix composite with polyphasic and multi-scale ceramic particles

Hybrid aluminum matrix composites have received widespread attention because of their superior performance to single-phase reinforced aluminum matrix composites. In situ VB2–AlN–Al4C3–VSi2/Al ribbons with polyphasic and multi-scale reinforcement particles were prepared by powder metallurgy method and controlled by melt-spinning and then verified the reinforcement efficacy in Al–12Si alloy. It was found that the addition of VB2–AlN–Al4C3–VSi2/Al ribbons not only refined the grain of α-Al, but also optimized the morphology of eutectic silicon for Al–12Si matrix composite. Thereafter, the mechanical properties of the VB2–AlN–Al4C3–VSi2/Al–12Si composite, including the tensile strength, ductility and hardness were increased by 36.2%, 82.2% and 33.4%, respectively, with the addition of VB2–AlN–Al4C3–VSi2/Al ribbons. The excellent mechanical properties can be attributed to the micron-sized VSi2 particles, nano-sized AlN, VB2, and Al4C3 as well as the well-bonded particle/matrix interface. In addition, multiple strengthening mechanisms have also made outstanding contributions to the improvement of the mechanical properties, including (1) Orowan strengthening; (2) Coefficient of thermal expansion (CTE) mismatch strengthening; (3) the Hall-Petch effect caused by grain refinement. The present experimental results provide an insight into the understanding of polyphasic and multi-scale reinforcement particles, and extend the effort for the development of Al–Si composite.

Experimental study of the damage morphology induced by the millisecond–nanosecond combined-pulse laser with different pulse delay on silicon

The damage morphologies of silicon induced by ms-ns combined-pulse laser with different pulse delay are investigated, based on the experimental investigations of the temperature, plasma plume, and damage morphology. The splashing phenomenon began to be obvious when the pulse delay was 0.8 ms, and the small holes were formed on the center of damage morphology. It was found that the process of droplet ejection might occurred after the irradiation of ns laser. The mechanism of damage morphology induced by ms–ns combined-pulse laser with different pulse delays was discussed.

Preparation and characterization of NiO/PSi as self-cleaning surface

Water-resistant surfaces are very important to many modern technology applications. So the progresses of hydrophobic & hydrophilic surfaces for self-cleaning applications has received widespread attention over the past years. In this paper, investigating in self-cleaning surfaces technique are presented. Nickel oxide Nanoparticles (NiONPs) were manufactured at different concentrations on the porous silicon (PSi) surface by immersion plating process, which filled with square-pores like structure which affected in classification of hydrophilic and hydrophobic surfaces. This green method to prepare Nickel oxide Nanoparticles/porous silicon (NiONPs/PSi) structures was interesting because it is effective for self-cleaning applications and is low cost and environmentally friendly. NiONPs/PSi structures characterized by the use of X-Ray Diffraction, electron microscopy scanning, Fourier-transform infrared (FTIR) analysis, Ultraviolet–visible (UV) spectroscopy, and contact angle analysis. The results show that hydrophilicity & hydrophobicity of these structures strongly depend on the surface morphology of porous silicon and the resulting the shape and distribution of NiO nanoparticles. From all results, it was found that the optimum contact angle is 118° at a NiO concentration of 10-2 M for the NiONPs/PSi structure which has hydrophobic properties as it can be used as a self-cleaning surface.

Influence of two different range of sillimanite particle reinforcement on tribological characteristics of LM30 based composites under elevated temperature conditions

In this work, high temperature wear-resistant LM30/sillimanite composites for automotive applications have been fabricated. Dual particle size composites reinforced with naturally occurring sillimanite mineral were processed and investigated for operating temperatures in the range of 50–300 °C. Sillimanite particles with size range of 1–20 μm (fine) and 75–106 μm (coarse) were mixed in weight ratio of 3:1, 1:1, and 1:3 to be reinforced to the LM30 alloy. SEM micrographs and area mapping/line mapping profile results showed presence of different phases and revealed that sillimanite inclusion changed the morphology of proeutectic silicon to globular and refined its grain size. Particles were well distributed in LM30 matrix. Increase in reinforcement level of particles led to continuous improvement in properties. As such, the best properties were obtained in composite containing 15 wt% sillimanite with proportion of fine: coarse particles as 3:1 (15-DPS3 composite). The transition temperature of wear mode increased from 150 °C for base alloy to 200 °C for composites. For the temperature-pressure condition of 200–1 MPa, 15-DPS3 composite showed 15% higher hardness, 80% lower wear rate, 48% lower friction coefficient, and 28% lower thermal expansion coefficient than base alloy. These wear characteristics of composites were comparable to the commercially used grey cast iron material. XRD of wear track/debris confirmed the formation of tribolayer. SEM analysis of wear track/debris identified the wear mechanisms causing materials loss under different contact pressures. Light-weight and economical composites developed in this research can act as a good substitute for the heavy cast iron components used in industry.

The effect of phosphorus on solidification behaviour of undercooled Al\u201370\xa0wt.%Si alloys

Effect of refining element phosphorus (P) on the morphology of the primary silicon in the Al–70 wt.%Si alloy was investigated via the electromagnetic levitation (EML) technique. The morphology and microstructure were analyzed by using high-speed video (HSV) and scanning electron microscopy (SEM). It was found that the morphology of primary silicon transformed from dendrites with several branches to blocky shape, and then to equiaxed grains in Al–70 wt.%Si and Al–70 wt.%Si–1.0 wt.%P alloys with increasing of undercooling. The nucleation number and nucleation rate increased exponentially with the increase of undercooling for both alloys. Finally, the growth velocity of primary silicon was discussed in combination with classical theory.

Corrosion of Cast Aluminum Alloys: A Review

Research on corrosion resistance of cast aluminum alloys is reviewed in this article. The effect of the main microstructural features of cast aluminum alloys such as secondary dendrite arm spacing (SDAS), eutectic silicon morphology, grain size, macrosegregation, microsegregation, and intermetallic compounds is discussed. Moreover, the corrosion resistance of cast aluminum alloys obtained by modern manufacturing processes such as semi-solid and additive manufacturing are analyzed. Finally, the protective effects provided by different coatings on the aluminum cast alloys—such as anodized, plasma electrolytic oxidation (PEO), and laser—is reviewed. Some conclusions and future guidelines for future works are proposed.

Analysis of Surface Morphology and Chemical Composition of Silicon Implanted with Copper Ions

We report on the results of analysis of the structure and chemical composition of the surface of c-Si single crystal substrates implanted with Cu+ ions with energy of 40 keV and doses in a range of 3.1 × 1015–1.25 × 1017 ions/cm2 for a current density of 8 μA/cm2 in the ion beam. It has been established using scanning electron microscopy and probe microscopy combined with X-ray photoelectron and Auger spectroscopy that at the initial stage, the implantation with Cu+ ions to a dose of 6.25 × 1016 ions/cm2 induces the formation of Cu nanoparticles with an average size of 10 nm in the Si surface layer. Upon a further increase in the implantation dose, beginning with 1.25 × 1017 ions/cm2 and higher, the nucleation of the η phase of copper silicide (η-Cu3Si) is observed. This is due to heating of the surface layer of the Si substrate during its irradiation to a temperature facilitating the formation of the η-Cu3Si phase.

Optimizing the Microstructure and Mechanical Properties of Vacuum Counter-Pressure Casting ZL114A Aluminum Alloy via Ultrasonic Treatment

The effect of ultrasonic temperature on density, microstructure and mechanical properties of vacuum counter-pressure casting ZL114A alloy during solidification was investigated by optical microscopy (OM), scanning electron microscope (SEM) and a tensile test. The results show that compared with the traditional vacuum counter-pressure casting aluminum alloy, the primary phase and eutectic silicon of the alloy with ultrasonic treatment has been greatly refined due to the dendrites broken by ultrasonic vibration. However, the refining effect of ultrasonic treatment on vacuum counter-pressure casting aluminum alloy will be significantly affected by ultrasonic temperature. When the ultrasonic temperature increases from 680 °C to 720 °C, the primary phase is gradually refined, and the morphology of eutectic silicon also changes from coarse needle-like flakes to fine short rods. With a further increase in the ultrasonic temperature, the microstructure will coarse again. The tensile strength and elongation of vacuum counter-pressure casting ZL114A alloy increases first and then decreases with the increase of ultrasonic temperature. The optimal mechanical properties were achieved with tensile strength of 327 MPa and the elongation of 5.57% at ultrasonic temperature of 720 °C, which is 6.3% and 8.2%, respectively, higher than that of alloy without ultrasonic treatment.

Luminescent Porous Silicon Filled with Nanoscopic Magnetic Structures – Assessment of the Optical and Magnetic Properties

Luminescent porous silicon which is denoted as microporous silicon offers a structure size of a few nanometers. It is filled with magnetic metals resulting in a composite system with specific optical and magnetic properties. The morphology of microporous silicon offers a branched network of pores. The luminescence which is observed in the red-orange region due to the small structure size is influenced by the metal filling. The magnetic response of the samples is related to the interconnected pores and differs significantly to mesoporous silicon filled with magnetic nanostructures of similar size.The luminescent porous silicon is etched in aqueous hydrofluoric acid solution by applying a current density of 10 mA/cm2 for 20 min resulting in a porous layer of about 0.8 µm thickness. The metal filling of microporous silicon is a challenging procedure which is carried out under cathodic conditions by pulsed electrodeposition. As electrolytes adequate metal salt solutions are used. The deposited nanosized metal structures are of the same interconnected sponge-like morphology as the template material.Mesoporous silicon offers oriented pores whereas the diameter is in the range of 50 nm [1]. Also in this case the metal nanoparticles are electrodeposited within the matrix material.The magnetic properties of the different systems rely on the morphology of the template material and the size and geometry of the incorporated metal deposits.The magnetic response offers a significant difference between filled luminescent and mesoporous silicon samples. Luminescent metal filled samples show strong magnetic anisotropy between the magnetization parallel and perpendicular to the surface. For these specimens also significant differences of the anisotropy can be observed depending on the kind of deposited metal, e.g. Ni or Co. These differences are not so distinctive in the case of mesoporous metal filled silicon because of weak magnetic interactions between the metal nanoparticles.Due to the merged optical and magnetic properties in the case of microporous silicon the nanocomposite could be promising for integrated magneto-optic devices.[1] P. Granitzer, K. Rumpf, Semiconductor Science and Technology 31, 4004, 2016.

Cavity resonance tunability of porous silicon microcavities by Ar+ ion irradiation

Present work reports the effect of low-energy Ar+ ion beam irradiation on the optical properties and surface morphology of porous silicon (PSi) based optical microcavities. These microcavities were realized by an active λ/2 spacer layer sandwiched between two Distributed Bragg Reflectors fabricated by galvanostatic electrochemical etching. Low-energy 10 keV Ar+ ions at various fluences were used for this irradiation study for these microcavities and characterized. The peak in the reflectance spectra of resonant cavity shows a red-shift after ion irradiation. These experimental observations are in good agreement with transfer matrix simulations. The Raman studies show that the crystalline Si is modified in nanostructured PSi and subsequently, the structural features of Si-Si and Si-O bonds. The simulated depth profiles suggest that the penetration of Ar+ ion is limited to top two PSi layers and the reduction of effective refractive index of these two layers. These experimental findings, analytical simulations, and cavity modelling provide the evidence of resonent cavity peak tunability, optical field intensity modulation, and photon confinement within the microcavity. This approach could be useful to tune the optical properties of PSi and an effective method for producing widely tunable optical structures in Si-based photonic architectures.

Properties investigation of crystalline silicon surface irradiated by nanosecond laser pulses in different background atmospheres

Black silicon materials were obtained by irradiation with ns laser pulses in different ambient atmospheres. The surface morphology, optical properties, and electrical properties of the black silicon were investigated after the ablation by ns laser pulses. Slab-like structures and boundaries were formed on the surface of black silicon fabricated in sulfur hexafluoride (SF6), argon (Ar), and vacuum. In addition, a micrometer-sized sphere was observed at the tip of the slab-like structure, which was not obvious for the black silicon prepared in oxygen (O2), nitrogen (N2), and air. The infrared absorption of all the black silicon materials was enhanced. For the two samples fabricated in SF6 and Ar, the infrared absorptance was approximately 50% at 1500 nm. A post-thermal annealing process decreased the infrared absorptance of all the black silicon materials except for that prepared in SF6. The sheet resistance of the black silicon was reduced by the ns laser irradiation process, and thermal annealing further decreased the sheet resistance of all the samples except for the one fabricated in SF6. After annealing at 875 K, the sheet carrier density of the black silicon fabricated in an Ar atmosphere and vacuum was approximately 1013 cm−2, which was approximately three orders of magnitude larger than that of the silicon substrate (1010 cm−2). The large difference in carrier density between the black silicon layer and substrate is beneficial for establishing contact junctions and for application in infrared photodetection.

Effect of etching time in hydrofluoric acid on the structure and morphology of n-type porous silicon

We studied the influence of etching time in hydrofluoric acid and methanol solution on the structure and morphology of n-type porous silicon (PSi). Dissolution of Si in the solution of hydrofluoric acid with methanol with surface oxidation occurs. All investigated samples reveal pores with increasing average size proportional to the etching time. Areic density and RMS roughness observed by scanning electron and atomic force microscopies have maximum for 10 min etching time. Additional etching time leads to slight increase in the pore size diameter and decreasing the RMS roughness of layers. All amorphous PSi samples are covered with the SiO2 layer containing probably HySiOx and SiFxHy complexes. The presence of SiH complexes leads probably to the growth of PSi layers with pores. The thickness of this layer depends on etching time and probably contains HySiOx and SiFxOy complexes.

The effect of heat treatment on die casting aluminum to apply self-pierce riveting

Vehicle weight reduction has been discussed by automotive industry for decades. The current solution for weight reduction purpose is the use of aluminum stamping and casting parts to replace the steel parts. However, joining aluminum with aluminum or aluminum with steel parts would be difficult to select a proper joining technology to ensure a qualified joint. Self-pierce riveting (SPR) as a mechanical joining technique has been used by automotive industry owing to its simplicity, versatility, and environment friendly nature. Although SPR can avoid the joining quality problems caused by welding to join aluminum with steel parts, the other joining problems from SPR still hinder the industry to widely use this joining technology. This article analyzed the cause of cracks on joint button from the understanding of joined material. The modified heat treatments were used to investigate the relationship between eutectic silicon morphology and cracking condition on joint button. In addition, the lap-shear strength according to the samples with various heat treatments was also tested and analyzed. Eventually, the results indicated that silicon content and its morphology take main responsibility on crack initiation and propagation on SPR joint button. But the influence of cracks on joining strength still needs to be investigated and studied in the future work.