Papers by Keyword: Monocrystalline Silicon

Abstract: In this work a special electrode configuration with potential application in enzymatic biosensors for the detection of glyphosate was studied. The enzyme used was Horseradish Peroxidase (HRP), which was immobilized on a polyaniline film (PAni), electrodeposited on the surface of the n-type monocrystalline silicon electrode. PAni has the ability to bind to biomolecules and thereby potentiate their biocatalytic properties by favoring the transfer of electrons between enzyme and substrate. Monocrystalline silicon is one of the most used materials in electronic technology due to its semiconductor character. In this work, different parameters were investigated in the electrode preparation, including concentration of polyaniline in the electrodeposition solutions, as well as the electrodeposition times and potentials. The response of the electrode as biosensor was evaluated by the electric current density characteristic of hydroquinone oxidation in the presence of standardized glyphosate solutions. The peroxidase enzyme catalyzes the oxidation of hydroquinone to the o-quinone form in the presence of hydrogen peroxide. In turn, glyphosate inhibits the activity of HRP and causes a reduction of the electric current density in the biosensor electrode. The results obtained with glyphosate using the proposed method are in agreement with the literature and show that the n-Si/PAni/HRP biosensor maintains the catalytic activity and is of considerable interest due to the simple procedure in practical applications and a promising platform for the lack of environmental monitoring for these contaminants.

Abstract: In this paper, material removal mechanism of monocrystalline silicon by chemical etching with different solutions were studied to find effective oxidant and stabilizer. Material removal mechanism by mechanical loads was analyzed based on the measured acoustic signals in the scratching processes and the observation on the scratched surfaces of silicon wafers. The chemical mechanical polishing (CMP) processes of monocrystalline silicon wafers were analyzed in detail according to the observation and measurement of the polished surfaces with XRD. The results show that H₂O₂ is effective oxidant and KOH stabilizer. In a certain range, the higher concentration of oxidant, the higher material removal rate; the higher the polishing liquid PH value, the higher material removal rate. The polishing pressure is an important factor to obtain ultra-smooth surface without damage. Experimental results obtained silicon polishing pressure shall not exceed 42.5kPa.

Abstract: A three-dimensional molecular dynamics (MD) simulation is conducted to investigate the effect of the abrasive rotating velocity on monocrystalline silicon specimen by mechanical polishing at atomistic scale. By monitoring relative positions of atoms in the monocrystalline silicon specimen, the microstructure of monocrystalline silicon is clearly identified and analyzed. The simulation results show that better machined surface quality is obtained and more phase transformation atoms occur with small abrasive rotating velocity. When the abrasive rotating is high, the surface quality deteriorates and amorphous layer thickens.These results provide us an effective approach to analyze the mechanism of material deformation and the formation of the machined surface after ultra-precision polishing.

Abstract: Solar energy is the inexhaustible,enewable Energy. The solar cell is the solar light energy into electricity. The unique advantages of solar cell. Potential, more than wind, hydro, geothermal energy, nuclear energy and other resources, is expected to become the main pillar of power supply in the future. This paper studies that the main parameters of monocrystalline crystal silicon solar battery: the junction depth and superficial concentrations influence on electrical characteristics of monocrystalline silicon solar battery. The result shows that for maximum efficiency, it is bound to get the largest possible open circuit voltage, short circuit current and fill factor of the product, therefore, it is necessary to control these two parameters, the junction depth and doping parameters. If the junction depth is constant, with the increased superficial doping concentration of monocrystalline silicon solar battery, the photoelectric conversion efficiency of the battery increases slowly at first and then rapidly decreases, and the deeper the junction depth is, the more obvious trend of the photoelectric conversion efficiency is.

Abstract: A series of three-dimensional molecular dynamics (MD) simulations of nanoindentation are conducted to investigate the deformation behavior and phase transformation of monocrystalline silicon with different size hemispherical diamond indenters on (010) crystal plane. The technique of coordination number (CN) is employed to elucidate the detailed mechanism of phase transformation in the monocrystalline silicon. The simulation results show that the phase transformation varies according to the different radii indenters. In the phase transformation region beneath the indenter, the crystalline structures of Si-II, Si-XIII, and amorphous phase structures are observed. In addition, the results indicate that phase transformation with large indenters is not same with the small indenter. The six-coordinated silicon phase, Si-XIII, transformed from Si-I is identified. The phases of Si-II and Si-XIII, which have the same coordinate number, are successfully extracted from the transformation region during nanoindentation and amorphous phase will emerge upon unloading.

Abstract: Monocrystalline silicon is typical of hard brittle materials, a high surface quality can be obtained in ductile-regime cutting. The success of the turning process depends on optimizing the machining parameters such as the tool edge radius, tool rake angles, depth of cut and cutting speed, etc. In this study, based on the ductile–brittle transition mechanism, the optimization of cutting parameters were determined with the commercial, general purpose FEA software Msc.Marc. The result demonstrates that the value of temperature is minimum when the tool rake angle is in the range of -15º～-30º. Smaller tool edge radius was selected while maintaining quality of tool edge radius and tool life. As long as beyond the range of cutting speed 6 ~ 8 mm/s, smaller residual stress can be obtain.

Abstract: A three-dimensional model of molecular dynamics (MD) was employed to study the nanometric cutting mechanism of monocrystalline silicon. The model included the utilization of the Morse potential function to simulate the interatomic force between the workpiece and the tool, and the Tersoff potential function between silicon atoms. Amorphous phase transformation and chip volume change are observed by analyses of the snapshots of the MD simulation of the nanometric cutting process, energy and cutting forces. Dislocations and elastic recovery in the deformed region around the tool do not appear. Cutting forces initiate the amorphous phase transformation, and thrust forces play an important role in driving the further transformation development. Nanometric cutting mechanism of monocrystalline silicon is not the plastic deformation involving the generation and propagation of dislocations, but deformation via amorphous phase transformation.

Abstract: The application of solar cell has offered human society renewable clean energy. As intelligent materials, crystalline silicon solar cells occupy absolutely dominant position in photovoltaic market, and this position will not change for a long time in the future. Thereby increasing the efficiency of crystalline silicon solar cells, reducing production costs and making crystalline silicon solar cells competitive with conventional energy sources become the subject of today's PV market. The working theory of solar cell was introduced. The developing progress and the future development of mono-crystalline silicon (c-Si), poly-crystalline silicon (p-Si) and amorphous silicon (a-Si) solar cell have also been introduced.

Abstract: The physical model of fixed-abrasive diamond wire-sawing monocrystalline silicon was founded to analyze the elastic deformation of the wire, supposing that every grit was connected to the surface of the wire by a spring. Ignoring lateral vibration of the wire, the geometrical model of wire-sawing was founded; the average cut depth of single grit was calculated theoretically. Based the indentation fracture mechanics and investigations on brittle-ductile transition of machining monocrystalline silicon, the removal mechanism and surface formation was studied theoretically. It shows that in the case of wire-sawing velocity of 10m/s or higher, infeed velocity of 0.20mm/s and diamond grain size of 64μm or smaller, the chip formation and material removal is in a brittle regime mainly, but the silicon wafer surface formation is sawed in a ductile regime. The size of the abrasives, the wire-saw velocity and infeed velocity can influence the sawing process obviously.

Abstract: This paper presents the molecular dynamics (MD) simulation of nano-indentation of diamond-like carbon (DLC) coating on silicon substrates. It is found that the mechanisms of nanoindentation of coated systems on the nanometre scale defers considerably from the same process on the micrometre scale. The coating thickness affects the mechanisms of plastic deformation both in the coating and the substrate.