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Nondestructive nanofabrication on monocrystalline silicon via site-controlled formation and removal of oxide mask
摘要： A nondestructively patterned silicon substrate serves as an ideal support for forming high-quality optical structures or devices. A new approach was proposed for fabricating site-controlled structures without destruction on a monocrystalline silicon surface via local anodic oxidation (LAO) and two-step postetching. The nondestruction was demonstrated by conductivity detection with conductive atomic force microscopy (AFM), and an almost perfect crystal lattice was observed from the fabricated hillock by high-resolution transmission electron microscopy (HRTEM). By programming AFM tip traces for LAO processing, site-controlled nondestructive patterns with di?erent layouts can be produced. This approach provides a new route for realizing nondestructive optical substrates.
关键词： conductive atomic force microscopy,high-resolution transmission electron microscopy,local anodic oxidation,nondestructive nanofabrication,monocrystalline silicon
更新于2025-11-14 17:04:02
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Generation and distribution of residual stress during nano-grinding of monocrystalline silicon
摘要： Residual stress generated in grinding process of monocrystalline silicon can cause the wafer warpage, and di?culties in subsequent processes such as holding and scribing. It can also lead to the formation of cracks and the occurrence of corrosion, which is harmful for electrical performance of silicon component. In this study, with the method of step-wire wet etching, the phase transformation and distribution of residual stress in ground silicon wafer were examined by confocal laser micro-Raman spectroscopy. As the etching depth going down, the residual stress exhibits in the trends of decreasing of compressive stress and following a scatter distribution of tensile stress. During the nano-grinding processes of monocrystalline silicon, the generation mechanism of residual stress is computed by a series of the molecular dynamic (MD) simulation. Subsurface damage (SSD) in the form of phase-transformed silicon is observed, and the depth of SSD varies by the depth of cut. The volume shrinkage of phase-transformed silicon is also studied to explain the grinding mechanism and the reason for inducing residual stress of ground silicon. By adopted the Stony theory and volume shrinkage rate of amorphous phase from MD results, a theoretical model is established to determine the trend of compressive stress in subsurface of ground silicon.
关键词： monocrystalline silicon,residual stress,nano-grinding,phase transformation,molecular dynamics
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Enhancing Photocarrier Bulk Lifetime with Defect Engineering of Polycrystalline Passivated-Contact n-Cz Photovoltaic Devices
摘要： We study the photocarrier lifetime evolution of n-Cz Si material throughout the processing sequence for polycrystalline passivated contact devices. We show that a high temperature annealing pretreatment (known as Tabula Rasa) has a clear effect on enhancing bulk lifetimes of n-Cz Si. We further this development by integrating such defect engineering into the lower-temperature annealing of passivated contact. By applying oxidizing ambient gases during these anneals we report a photocarrier lifetime enhancement over an N2 environment. This enhancement is exhibited in a 1-sun iVOC of 735 mV when annealed in O2 rather than 708 mV in N2.
关键词： monocrystalline silicon,intrinsic point defects,passivation,thermal processing,Czochralski,photocarrier lifetime
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - High-Efficiency Corrugated Monocrystalline Silicon Solar Cells with Multi-Directional Flexing Capabilities
摘要： High efficiency, lightweight and low cost flexible solar cells have attracted a growing interest in the last decades due to their increased applications. Here, we show high-efficiency (19%) and large scale (5 × 5 inch wafer) monocrystalline silicon solar cells with multi-directional flexing capabilities. The flexing of rigid solar cells with interdigitated back contacts is achieved using a photolithography-less corrugation technique. Results show that linear patterns enable flexibility in one direction with a minimum bending radius of 5 mm while diamond patterns result in multi-directional flexibility with different minimum bending radii and robust electrical performance.
关键词： monocrystalline silicon,multi-directional flexing,flexible solar cells,corrugation technique,high efficiency
更新于2025-09-23 15:19:57
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Corrugation Enabled Asymmetrically Ultrastretchable (95%) Monocrystalline Silicon Solar Cells with High Efficiency (19%)
摘要： Stretchable solar cells are of growing interest due their key role in realizing many applications such as wearables and biomedical devices. Ultrastretchability, high energy-efficiency, biocompatibility, and mechanical resilience are essential characteristics of such energy harvesting devices. Here, the development of wafer-scale monocrystalline silicon solar cells with world-record ultrastretchability (95%) and efficiency (19%) is demonstrated using a laser-patterning based corrugation technique. The demonstrated approach transforms interdigitated back contacts (IBC) based rigid solar cells into mechanically reliable but ultrastretchable cells with negligible degradation in the electric performance in terms of current density, open-circuit voltage, and fill factor. The corrugation method is based on the creation of alternating grooves resulting in silicon islands with different shapes. The stretchability is achieved by orthogonally aligning the active silicon islands to the applied tensile stress and using a biocompatible elastomer (Ecoflex) as a stretchable substrate. The resulting mechanics ensure that the brittle silicon areas do not experience significant mechanical stresses upon asymmetrical stretching. Different patterns are studied including linear, diamond, and triangular patterns, each of which results in a different stretchability and loss of active silicon area. Finally, finite element method based simulation is conducted to study the generated deformation in the different patterned solar cells.
关键词： stretchable electronics,monocrystalline silicon,photovoltaics,interdigitated back contacts,corrugation
更新于2025-09-19 17:13:59
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The influence of the pyramidal texture uniformity and process optimization on monocrystalline silicon solar cells
摘要： To improve the photoelectric conversion efficiency of monocrystalline silicon solar cells, the influence of the pyramidal texture uniformity on the defects in the monocrystalline silicon cells was analyzed by simulation, and the uniformity of the pyramidal texture was quantitatively characterized with the uniformity coefficient. The texturing process parameters were optimized by fitting and optimizing the uniformity coefficient. In the experiments herein, four groups of textured monocrystalline silicon wafers were obtained by treating them with a 1.2% sodium hydroxide (NaOH) solution for four different times. The uniformity coefficient of each monocrystalline silicon wafer group was obtained. By fitting the uniformity coefficient, we obtained the texturing process parameters corresponding to the maximum uniformity coefficient. The experimental results show that the optimized monocrystalline silicon cell achieved a pyramidal texture with a maximum uniformity coefficient. In addition, the reflectivity of the monocrystalline silicon cell reached a minimum value, and the photoelectric conversion efficiency reached a maximum value. The uniformity coefficient can not only effectively quantify the uniformity of the pyramidal texture but also effectively optimize the texturing process parameters to improve the photoelectric conversion efficiency of monocrystalline silicon cells.
关键词： pyramidal texture uniformity,texturing process optimization,uniformity coefficient,photoelectric conversion efficiency,monocrystalline silicon solar cells
更新于2025-09-19 17:13:59
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A new uniformity coefficient parameter for the quantitative characterization of a textured wafer surface and its relationship with the photovoltaic conversion efficiency of monocrystalline silicon cells
摘要： A new parameter, the uniformity coefficient (UC), was proposed to overcome the difficulty in quantitatively characterizing the uniformity of the pyramidal textured surface of silicon wafers widely used for monocrystalline silicon cells (MSCs). The UC was defined based on the areal material ratio Smr(c) from the standard ISO 25178-2. First, the values of Smr(c) for MSC wafer surfaces with a uniform texture and an arbitrary texture were calculated. For the ideal uniform texture, Smr(c) was calculated using one pyramid assuming equal pyramids distributed over the wafer surface. For any arbitrary texture, based on the pyramidal geometrical structure, Smr(c) was calculated from the heights of pyramids extracted from their 2D projections. Second, the areas bounded by the Smr(c) curves with two coordinate axes were calculated accordingly. Then, the ratio of the two areas was defined as the UC. Fifteen kinds of monocrystalline silicon wafers were prepared by chemical texturing for 5 min, 15 min, 25 min, 35 min and 45 min with three groups of solutions, and the corresponding MSCs were fabricated. The UCs of the fifteen silicon wafers and the photovoltaic conversion efficiencies (PCEs) of the MSCs were tested. The relationships between the UC, texturing process (solution and time) and PCE were analyzed. The PCE increased monotonically with an increase in the UCs The silicon wafer obtained by texturing with 2% TMAH solution for 25 min had a textured surface with a maximum UC of 0.89, and the MSC exhibited a maximum PCE of 20.3%. The experimental results indicated that the UC is an effective parameter for the quantitative characterization of the pyramidal texture of silicon wafer surfaces and has a definite relationship with the PCE of the MSC. The UC is a useful and convenient measure for texturing process optimization.
关键词： Uniformity coefficient (UC),Quantitative characterization,Monocrystalline silicon cell (MSC),Pyramidal texture,Photovoltaic conversion efficiency (PCE),Areal material ratio Smr(c)
更新于2025-09-16 10:30:52
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Crystal defects in monocrystalline silicon induced by spot laser melting
摘要： Laser processing of monocrystalline silicon has become an important tool for a wide range of applications. Here, we use microsecond spot laser melting as a model experiment to investigate the generation of crystal defects and residual stress. Using Micro-Raman spectroscopy, defect etching, and transmission electron microscopy, we find no dislocations in the recrystallized volume for cooling rates exceeding jdT=dtj ? 2 (cid:2) 107 K/s, and the samples remain free of residual stress. For cooling rates less than jdT=dtj ? 2 (cid:2) 107 K/s, however, the experiments show a sharp transition to a defective microstructure that is rich in dislocations and residual stress. Moreover, transmission electron microscopy indicates dislocation loops, stacking-fault tetrahedra, and voids within the recrystallized volume, thereby indicating supersaturation of intrinsic point defects during recrystallization. Complementing photoluminescence spectroscopy indicates even three regimes with decreasing cooling rate. Spectra of regime 1 do not contain any defect related spectral lines. In regime 2, spectral lines appear related to point defect clusters. In regime 3, the spectral lines related to point defect clusters vanish, but dislocation-related ones appear. We propose a quantitative model explaining the transition from dislocation-free to dislocation-rich recrystallization by means of the interaction between intrinsic point defects and dislocations.
关键词： monocrystalline silicon,transmission electron microscopy,laser melting,micro-Raman spectroscopy,crystal defects,residual stress,photoluminescence spectroscopy
更新于2025-09-16 10:30:52
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Determination of Technological Features of a Solar Photovoltaic Cell Made of Monocrystalline Silicon P <sup>+</sup> PNN <sup>+</sup>
摘要： The development in the field of semiconductor materials and electronic devices has a great impact on systems with renewable energy sources. Determination of the functional parameters of photovoltaic solar cells is essential for the subsequent usage of these semiconductor devices. Research was made on type P+PNN+ monocrystalline silicon wafers. Crystallographic measurements of the photovoltaic solar cell were made by means of FESEM-FIB Auriga Workstation. Initial data were selected from the study of models found in the specialized literature. The experimental results were compared to classical mathematical models. Measurements made on the photovoltaic solar cell were realised in laboratory conditions on the NI-ELVIS platform produced by National Instruments.
关键词： P+PNN+,NI-ELVIS platform,monocrystalline silicon,FESEM-FIB Auriga Workstation,photovoltaic solar cells
更新于2025-09-12 10:27:22
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Cylindrical and plane surface electromagnetic waves in laser technology of silicon surface texturing with a double femtosecond pulse
摘要： This paper presents experimental results of laser modification of the surface of monocrystalline silicon under the influence of a double femtosecond laser pulse with varying delays less than or close to the electron–phonon interaction time, as well as the results of numerical simulation of the photoexcitation of a semiconductor in the approximation of dielectric constant. It is shown that the excitation of cylindrical surface waves not only precedes the excitation of plane surface electromagnetic waves, but is also a determining factor in the cumulative change in the dielectric constant of the medium and the creation of conditions for the excitation of plane surface electromagnetic waves.
关键词： Femtosecond texturing of the surface,Cylindrical surface electromagnetic waves,Monocrystalline silicon,Surface electromagnetic waves,Double femtosecond laser pulse
更新于2025-09-11 14:15:04