Monocrystalline Silicon Research Articles

Experimental investigation of nonuniform PV soiling

Photovoltaic (PV) module soiling, i.e., the accumulation of dust on PV module surfaces, poses several challenges to PV system performance. Among these challenges, the nonuniform deposition of soiling across the module surface has received scarce attention. Soiling is directly associated with an overall performance loss, but can also potentially give rise to localised hotspots that can lead to long-term PV module failure. Therefore, addressing the issues arising from this nonuniformity is not only important for optimising energy production, but also for enhancing system reliability, and ensuring the long-term operation of relevant power generation systems. In this study, the impact of nonuniform soiling on PV performance is investigated experimentally by examining soil deposition on the upper surfaces of low-iron glass samples. Samples positioned at four different tilt angles were collected on a monthly basis over a one-year study period. Since the horizontal samples were found to represent the worst-case conditions, the most soiled sample at horizontal tilt was divided into four zones, each housing a single monocrystalline solar cell and examined further. The findings reveal that the soiled sample experiences an average transmittance deterioration of 13% relative to a clean sample, and a maximum (relative) spatial variation of 4% between the four zones. These optical losses affect the amount of sunlight received by the cells, resulting in a power deterioration of ∼6–7% per 5% drop in transmittance. The soiled sample experienced an average temperature rise of 2 °C, and an average power output (and efficiency) reduction of 30% relative to the clean sample, and a maximum (relative) spatial variation of 7% between the zones. The 30% average power loss measured in this nonuniform soiling case is more than double that which would be expected theoretically for a transmittance loss of 13% but from uniform soiling, so these results highlight the importance of addressing PV soiling for optimal PV performance, and of accounting for spatial soiling nonuniformity.

A proposal and simulation analysis for a novel architecture of gate-all-around polycrystalline silicon nanowire field effect transistor

A proposal for a novel gate-all-around (GAA) polycrystalline silicon nanowire (poly-SiNW) field effect transistor (FET) is presented and discussed in this paper. The device architecture is based on the realization of poly-SiNW in a V-shaped cavity obtained by tetra methyl ammonium hydroxide (TMAH) etch of monocrystalline silicon (100). The device’s behavior is simulated using Silvaco commercial software, including the density of states (DOS) model described by the double exponential distribution of acceptor trap density within the gap. The electric field, potential, and free electron concentration are analyzed in different nanowire regions to investigate the device's performance. The results show good performance despite the high density of deep states in poly-SiNW. This can be explained by the strong electric field caused by the corner effect in the nanowire, which favors the ionization of the acceptor traps and increases the free electron concentration.

The impact of some environmental variables on the performance of solar PV module

The country of Iraq tops the list of countries in solar activity and therefore has the most important renewable energy sources, which we desperately need to fill the acute shortage of electrical energy. The availability of this source coincides with a significant rise in temperature in most of its regions and a wide range of days of the year. Where temperatures play a key role in wind activity and the provocation of dust storms, which urgently requires a field study to find out the impact of these factors on the performance of photovoltaic solar modules. Therefore, this study aimed to evaluate the performance of the solar module under the influence of dust accumulation, temperature and wind speed. A group symmetric of monocrystalline silicon solar modules have been experimented to see how these factors affect the performance of the modules. The results showed that there is a clear impact by the heat factor and dust accumulation on the performance of solar modules, but the wind factor is the least influential and what can be concluded is that Iraq, especially the city of Baghdad, is an ideal place to invest solar energy in the production of electrical energy.

The picosecond laser ablation mechanism of monocrystalline silicon by coupling two-temperature model (TTM)-Molecular dynamic (MD)

Monocrystalline silicon is the most widely used material in microchips, microsensors and photovoltaic systems, where ultrashort pulse laser has been applied in grooving and holing. This paper investigates the ablation mechanism of monocrystalline silicon by picosecond laser, where a TTM-MD (Two-temperature model-Molecular dynamics) model was established based on the interaction theory between ultrashort pulse laser and Si. The effects of plasma shielding and surface reflectivity on the laser irradiation energy are investigated to analyze the variation of carrier temperature, lattice temperature and carrier density on the monocrystalline silicon surface. The occurrence of material melting, bubble nucleation and phase explosion are simulated to explore the material removal mechanism and the effect of laser fluence on the ablation behavior. The simulation model was finally verified by the ablation threshold experiments where a high-speed camera was applied to monitor the ablation process.

Experiment Comparative Analysis of Feed Rate with Velocity Control in Cutting Mono Crystalline Silicon Using a Diamond Wire Saw.

Fixed-diamond abrasive wire saw cutting is one of the most common methods for cutting hard and brittle materials. This process has unique advantages including a narrow kerf and the ability to use a relatively small cutting force. In the cutting process, controlling the main process parameters can improve the processing efficiency, obtaining a better processing surface roughness. This work designs the PI controller (Proportional-Integral controller) based on the reciprocating wire saw cutting process. The control objects are the workpiece feed rate and wire saw velocity, and the control objective is the normal cutting force. For the control trials, several reference values of various normal cutting forces were chosen. The effects of feed rate and saw velocity on the cutting surface finish and cutting time were investigated in this work using wire saw cutting analysis on a square monocrystalline silicon specimen. The results of this study showed that under a constant applied force of 2.5 N, the optimal feed rate of the diamond wire through the specimen could reduce cutting time by 42% while achieving a 60% improvement in the measured surface finish. Likewise, optimal control of the wire saw velocity could reduce cycle time by 18% with a 45% improvement in the surface finish. Consequently, the feed speed control is more effective than the wire saw velocity.

RF sputtered metal oxide layers as ARCs to improve photovoltaic performance of commercial monocrystalline solar cell

The rf-sputtered ZnO, MgO and Al2O3 transition metal oxide nano layers were developed as efficient antireflection coatings (ARCs) on commercial monocrystalline silicon (m-Si) photovoltaic cells. Wavelength dependence reflectance measurements show minimal reflectance (i.e., ∼1.3–2.0%) between 350 and 800 nm wavelength regions affirming antireflection behavior of oxide layers. The phase formation studies of these oxide layers display the crystalline phase however the presence of non-crystalline phase is noted in Al2O3 diffractogram pattern. Cross section microstructure characterization carried out using scanning electron microscopy (SEM) to know the ARC layer thickness illustrates MgO, ZnO and Al2O3 layers with coating thickness around 85 nm, 87 nm and 77 nm respectively. Also, the thickness of antireflection coatings computed using wavelength dependent refractive index measurement is consistent with cross section microstructure images. Photon to energy conversion (PEC) of ARC coated device under 1 sun condition display 1.99%, 1.07% and 0.39% improvement in efficiencies compared with commercial m-Si-solar cell endorsing suitability of selected transition metal oxides as efficient ARC materials. The external quantum efficiency (EQE) measurements show notable improvement in efficiency for MgO, ZnO and Al2O3 coated devices reaffirming their usability as efficient ARC materials on commercial m-Si-solar cells.

Monocrystalline silicon crystal line detection based on the improved YoloX-tiny algorithm

Monocrystalline silicon crystal line detection based on the improved YoloX-tiny algorithm

Techno-economic analysis and eco-efficiency indicators of a biomass-solar hybrid renewable energy system for João Pinheiro City

The study aims to rapidly scale up Hybrid Renewable Energy System (HRES) specifically emphasizing bioenergy generation for isolated rural communities. It aims to identify the most profitable and efficient configuration for HRES biomass-solar in João Pinheiro, taking advantage of local eucalyptus production to reduce costs associated with the transport of biomass waste, considering energy, economic and ecological indicators. Eucalyptus waste was chosen as the source of biomass as fuel, the Downdraft gasifier with air as the gasification agent, and monocrystalline silicon technology was selected for photovoltaic modules. Two case study scenarios were proposed based on global efficiency calculations. The techno-economic analysis was applied based on the First Law of Thermodynamics and the Levelized Cost of Electricity (LCOE) method. Case 2 showed the overall energy efficiency of 17.43% and LCOE 0.034 US$/kWh more suitable for HRES solar-biomass technology. Additionally, the eco-efficiency indicator indicator based on the calculated Net Present Value and ecological efficiency indicator, allowed evaluation of the relationship between added value and the environmental impacts associated with the studied configurations, with case 2 presenting 9.28e−05 kgCO2/US$ as best result. The conclusions show that the techno-economic analysis applied to the HRES syngas-solar, along with the eco-efficiency indicator, presents the viability of decentralized bioenergy supply, particularly in isolated rural communities. This innovative approach encourages sustainable measures to meet energy needs in isolated regions with climatic, environmental and biomass supply conditions like those of João Pinheiro.

Improving monocrystalline silicon surface quality with chemical mechanical polishing using the slurry with the additive of isopropanol

Enhancing the silicon surface smoothness with chemical mechanical polishing (CMP) is crucial to achieve better beam quality in X-ray systems. The additive in CMP slurry is the key factor in determining the resulting surface morphology. This paper exploits the effect of isopropanol (IPA) additive on regulating the material removal process and resulting microscopical surface morphology through varying the IPA concentration and polishing pressure. The improvement of surface quality and a dropping material removal rate (MRR) are obtained by increasing the IPA concentration from 0.1 to 2.5 mol/L. When the polishing pressure increases from 0.25 to 0.48 psi, a better surface quality and enhanced MRR are observed. By using the optimal polishing pressure of 0.48 psi and IPA concentration of 2.5 mol/L, the root-mean-square roughness can be reduced to 0.10 nm under a measurement area of 1 µm × 1 µm with atomic force microscopy, more than 58.3% lower compared to surfaces polished without IPA. This work suggests an approach to obtain the ultra-smooth silicon mirrors, which has promising applications in the field of X-ray, aerospace, and photovoltaics.

Polymer Additives Promoted Texturization on Monocrystalline Silicon for Solar Cell

The solar photovoltaic was well recognized as one of the major constituent parts in future green energy system to achieving carbon neutrality. Among various technological routes to improve photoelectric conversion efficiency, rational surface texturization on monocrystalline silicon is one of the most crucial and fundamental processing steps, so as to well control the micro/nano surface structure and obtain lower light reflectivity. Chemical wet etching was the current mainstream technology in photovoltaic industry, yet there is an urgent need to update green, efficient, customized texturization additives to meet the industrial demand. This minireview summarizes the history, key breakthrough and recent advance in texturization additives based on organic and polymer molecules as crucial chemicals, and provides perspective to development directions of future texturization additives.

Research on aerosol particles formed by laser interaction with various metals

Laser technologies are widely used in modern industry for cutting, welding, surface cleaning, drilling, and more, including in the nuclear industry for processing radioactively contaminated structures. These processes often lead to the formation of aerosol particles, including toxic nanoparticles, primarily oxides, which can penetrate cellular membranes and accumulate in the body. Understanding these particle formation processes is crucial for improving gas purification systems and personal protective equipment. This study utilized a ytterbium fiber pulsed-periodic laser (1.064 µm wavelength, 20 W power, 40 kHz pulse repetition rate, 200 ns pulse duration) to process various metals: aluminum (Al), bismuth (Bi), E110 alloy (Zr-based), carbon steel (St3), and stainless steel (08X18H10T). Aerosols were analyzed using a silicon monocrystalline substrate placed near the laser impact site, cleaned thoroughly to remove any contaminants. A 3D-printed model held the substrate at a 15-degree angle in the laser processing zone. Experiments were conducted in a closed box with local exhaust, positioning the substrate to capture the finest aerosol particles. Samples were analyzed using scanning electron microscopy (SEM) on a JEOL JSM-6480LV microscope. Results showed that aerosols formed consist of submicron agglomerates of particles smaller than 100 nm, with uneven deposition indicating air-borne agglomeration. Repeated scanning formed branched structures of interconnected nanoparticle agglomerates. In conclusion, laser processing with a 1.064 µm ytterbium fiber laser produces submicron aerosols of nanoparticles, presumably oxides. The deposition pattern suggests air-borne agglomeration, independent of the target material. These findings underscore the need for enhanced air purification and protective equipment to mitigate nanoparticle accumulation risks in respiratory organs and on skin during laser equipment operation.

A PV MPPT control method based on async-PSO and INC algorithm under shading condition

For the time being, solar energy has received considerable attention and development on account of its distinct advantages, such as rich reserves and no geographical restrictions. Nevertheless, in practical applications, the photovoltaic module is easily affected by external environments, which gives rise to a decrease in photovoltaic power. The maximum power point tracking (MPPT) technology for PV power system is an effective method to elevate the efficacy of photovoltaic electricity conversion. The frequently used control methods include the perturb and observe (P&O) algorithm and the incremental conductance (INC) method, and so forth; these methods vary tremendously in terms of the required parameters, algorithm complexity, tracking speed, tracking accuracy, hardware requirements etc. This work puts forth a MPPT control method on the basis of Async-PSO and INC algorithm to achieve a better performance in the MPPT. To reflect the change of light amplitude and temperature in a day, the temperature varies from 25℃ to 60℃ and irradiance from 450W/m2 to 900W/m2 . An extensively used mono-crystalline silicon PV module with 240W was considered as the research object to compare the capability of the recommended MPPT control method. MATLAB/Simulink software was adopted to model and simulate the algorithm. Aside from that, comprehensive comparisons were made with other MPPT methods to test and verify the recommended algorithm has significantly improved the tracking speed and accuracy at the maximum power point with smaller oscillations under various conditions.

Parylene-bonded micro-fluidic channels for cryogenic experiments at superfluid He-4 temperatures.

We present the manufacturing process of a (24.5 × 100) μm2-sized on-chipflow channel intended for flow experiments with normal and superfluid phases of 4He and showcase such a proof-of-concept experiment. This work proves the suitability of chip-to-chip bonding using a thin layer of Parylene-C for cryogenic temperatures as a simpler alternative to other techniques, such as anodic bonding. A monocrystalline silicon chip embeds the etched meander-shaped micro-fluidic channel and a deposited platinum heater and is bonded to a Pyrex glass top. We test the leak tightness of the proposed bonding method for superfluid 4He, reaching temperatures of ≈1.6K and evaluate its possible effects on flow experiments. We demonstrate that powering an on-chip platinum heater affects the superfluid flow rate by local overheating of a section of the micro-fluidic channel.

Impacts of spatial symmetries on stimulated Brillouin scatterings in nanoscale silicon waveguides: a theoretical and numerical study considering material anisotropies.

Fully considering the mechanical and photoelastic anisotropies of monocrystalline silicon, the impacts of spatial symmetries on the stimulated Brillouin scatterings (SBSs) in nanoscale suspended silicon waveguides are studied theoretically and numerically based on group theory. First, starting from an assumption that the principal material coordinate system can be arbitrarily orientated in a waveguide with fixed geometry, the silicon waveguides are systematically classified into a number of point groups according to their spatial symmetry features. Thereafter, the symmetry characteristics of physical fields and SBS opto-mechanical coupling characteristics in the silicon waveguides belonging to different point groups are further examined, and the major new findings can be summarized as follows: The SBS opto-mechanical couplings in several kinds of silicon waveguides with certain nontrivial symmetry features exhibit relatively predictable behaviors in that the opto-mechanical coupling coefficients can be deterministically vanishing or nonvanishing under very few constraints, which can thus serve as general symmetry selection rules for SBSs in suspended silicon waveguides. The results obtained in the present study could be a useful theoretical reference for the design of novel SBS-active silicon photonic devices.

The Influence of B4C Film Density on Damage Threshold Based on Monte Carlo Method for X-ray Mirror.

The uniformity and consistency of X-ray mirror film materials prepared by experimental methods are difficult to guarantee completely. These factors directly affect the service life of free electron laser devices in addition to its own optical properties. Therefore, the quality of the film material, especially the density, has a critical effect on its application. Boron carbide film and monocrystalline silicon substrate were suitable examples to explore their influence of density on the damage threshold based on Monte Carlo and heat-conduction methods. Through simulation results, it was found that the change in film density could affect the energy deposition depth and damage threshold. When the film density was 2.48 g/cm3, it had relatively high damage threshold in all energy ranges. And then the specific incident parameter for practical application was investigated. It was found that the damage mechanism of the B4C/Si was the melting of the interface. And the damage threshold was also higher with the film density of 2.48 g/cm3. Therefore, it was recommended to maintain the density at this value as far as possible when preparing the film, and to ensure the uniformity and consistency of the film material.

Дослідження розподілу кисню по довжині монокристалів кремнію, легованих компонентами з різним типом провідності

The purpose of the article is the study of convective flows and their influence on the growth of single crystals of silicon by the Czochralsky method from a large melt, which contributes to the emergence of non-stationary convection. Therefore, simulation of convection for the growth of silicon single crystals is an important step in the development of conditions for the growth of perfect single crystals. Silicon substrates are used to manufacture more than 90% of semiconductor devices and solar cells. A special role in the development of electronics is played by monocrystalline silicon, which is used for the manufacture of semiconductor devices and integrated microcircuits. The main requirements for the development of technology for the production of silicon substrates is an increase in quality at a decrease in cost. Promising technologies of 10-nm size and 3D-transistor structures significantly increase the requirements for uniformity of distribution of components, including layering in silicon single crystals. For the mathematical modeling of convective flows, melt flows were considered for a cylindrical crucible with a radius of 150 mm at a melt height of up to 40 mm. Such parameters ensure stationary convection in molten silicon. Methods of reducing stratification have been studied and developed for more than 50 years, but have not yet found a definitive solution. This method of single crystal growth is the most controlled and allows to influence the convective flows in the silicon melt below the phase interface with ultrasonic waves in the megahertz range. The effectiveness of using ultrasound in the extraction of semiconductor single crystals depends on the creation of special conditions for introducing them into the melt. 
 Reducing the influence of oxygen on the electrophysical properties of silicon single crystals is an intractable problem of silicon technology. One of the ways to solve this problem is alloying with an isomorphic impurity, for example, tin. The development of a method of doping single crystals of silicon with tin requires determination of its concentration in the liquid and solid phases

Investigation of cracking in monocrystalline silicon induced by high- temperature indentation

A simulation model of the indentation process via Berkovich indenter with cohesive interface elements and changeable temperature condition was developed. The indentation curves and imprints obtained by simulation were compared with experimental results. Compared with room temperature, the hardness of monocrystalline silicon decreases by 7.2 % at 400 °C, while it decreases dramatically by 64.3 % at 600 ℃. The initiation and expansion process of monocrystalline silicon cracks are investigated through the evolution of the scalar degradation parameter (SDEG). The original location of the half-penny crack changes from beneath the center of the imprint at room temperature to the edge region at 400 °C. The half-penny cracks were replaced by radial cracks at 500 ℃, and no crack formation occurs at 600 ℃. Stresses S11 and S22 were examined to investigate the evolution of surface and internal cracks in monocrystalline silicon. This analysis revealed the phenomenon of median crack closure under compressive stresses and a reduced cracking threshold under elevated temperatures.

Enhanced efficiency of mono-crystalline Si solar cells utilizing RF sputtered TiO2–Al2O3 blended anti-reflection coating for optimal sunlight transmission and energy conversion

Currently, surface reflection of incident sunrays over solar cells results in degradation of output performance of the solar cells. This can be sorted out using an antireflection coating. In this investigation, ARC materials such as Titanium dioxide (TiO2), Aluminium oxide (Al2O3) and blended TiO2– Al2O3 were utilized over the mono-crystalline Si (m-Si) solar cells. The ARCs for m-Si solar cell was coated using RF sputtering method. The optical, structural, electrical, I–V characteristics and temperature behavior of solar cell samples with coating and bare cells were studied. The elemental analysis was carried out using X-ray diffraction (XRD) method. The morphological study was conducted using High Resolution Transmission Electron Microscopy (HR-TEM) and Atomic Force Microscope (AFM). The electrical resistivity was measured in dark at room temperature using four-point probe technique. Optical characteristics was determined using UV–visible spectroscopy. It was discovered that the TiO2– Al2O3blend coated cell (I3) shows great performance than the other coatings. I3 solar cell demonstrated high power conversion efficiency (PCE) of 19.42 % and 20.16 %, when exposed to direct sunlight and neodymium radiation in both open and controlled environments. The findings indicate that TiO2– Al2O3blends are a suitable material for ARC applications, since they effectively reduce the incident photons scattering.

Decoupling analysis of stress components on monocrystalline silicon using angle-resolved oblique backscattering Raman spectroscopy

Decoupling analysis of stress components on monocrystalline silicon using angle-resolved oblique backscattering Raman spectroscopy

Study of side burr formation in steady-state nano-polishing of Si-wafer using molecular dynamics simulation

With advancements in the semiconductor industry, it is required to have angstrom level surface finish on silicon wafers which is achieved by nano-polishing. However, side burr is formed due to material pile-up from material removal due to abrasive which becomes detrimental to achieving the high surface finish. This study employs molecular dynamics simulations to explore the mechanism underlying side burr formation during nano-polishing of mono-crystalline silicon (Si)-wafer. The study utilizes a diamond nano-abrasive grit to scratch the surface of the Si-wafer and investigates the formation of pile-ups during the steady-state process. It was observed that increasing the depth of cut by four times led to a 6.3-fold increase in the number of amorphous atoms, indicating greater bond breakage in the direction of scratching. As a result, the cutting force exceeds the thrust force at larger depths of the cut. The correlation between the side burr height and the depth of cut is also studied. Results show that the side burr height ratio increases with the depth of cut, indicating a higher sensitivity of side burr height to the depth of cut. The study suggests that to achieve a ductile mode of material removal and minimize the height of the side burr during nano-polishing of Si-wafers, it is crucial to maintain the depth of cut at or below half (≤0.5) of the abrasive radius and ensure an average friction coefficient below 0.6. The outcome of this study can be useful for the actual manufacturing of miniaturized sensors, actuators, and microsystems for microelectromechanical system devices where a high surface finish is crucial.