Hybrid process for texturization of diamond wire sawn multicrystalline silicon solar cell

Acid texture is difficult for diamond wire sawn (DWS) multicrystalline silicon (mc‐Si) wafer owing to the inhomogeneous distribution of damage layer on the surface. In this article, metal‐assisted chemical etching (MACE) has been selected for introducing a porous seeding layer to induce acid texturing etching. SEM results show that the oval pit structures coverage get obvious improvement even on the smooth areas. Owing to the further improved light absorption ability by second MACE and nanostructure rebuilding (NSR) process, nanostructured DWS mc‐Si solar cell has exhibited a conversion efficiency of 17.96%, which is 0.45% higher than that of DWS wafer with simple acid texture process. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Surface texturing of Si, porous Si and TiO2 by laser ablation

Excimer laser ablation at 308 nm has been used to texture the surfaces of a variety of materials of interest for optoelectronic and biotechnological applications. Using a range of pre- and post-processing methods, we are able to produce nano-, micro- and meso-scale features over large areas rapidly in materials such as crystalline Si, porous silicon and TiO₂. Texturing of porous silicon leads to the growth of crystalline dendritic structures, which distinguishes them dramatically from the conical pillars formed from crystalline silicon. Regular arrays of Si microdots are formed by irradiating a Si surface pre-covered with a Cr thin film grating. Nano-crystalline porous TiO₂ films are easily ablated or compacted with laser irradiation. However, at low enough laser fluence, surface roughening without complete loss of porosity is possible.     

射频CO2激光用于轧辊毛化的实验研究

分析了轧辊材料在温度发生变化时对激光吸收系数的影响和毛化加工时各种工艺参数对毛化点的影响.针对Diamond K-50射频激励CO2激光器对轧辊毛化的实验,分析了激光脉冲宽度、重复频率以及毛化扫描速度等参数对毛化点的大小和椭圆度的影响,其中激光脉冲宽度与毛化点大小成线性关系,在脉宽为50～400μs时,毛化点椭圆短轴直径可达90～260μm,满足所需要的毛化加工要求.     

A two-step nanosecond laser surface texturing process with smooth surface finish

Surface texturing (for example, producing micro dimples on the surface) of mechanical parts has a great potential to improve the surface tribological properties. Surface texturing through nanosecond laser ablation has many associated advantages and hence has drawn lots of attentions. However, the produced micro dimple bottom (if through laser spot scanning) is often very rough, which may harm the surface tribological properties. In this paper, a two-step laser surface texturing process is proposed and studied, where a relatively high-fluence laser ablation step (which is to create dimples) is followed by a low-fluence laser-induced melting, melted material flow and re-solidification step (which is to smooth the ablated dimple bottom surface). The study shows that the two-step laser surface texturing process can produce dimples with very smooth bottom surfaces. The effects of laser pulse duration and scan speed in Step 2 on the dimple bottom surface morphology and roughness have also been investigated, and some very interesting physical phenomena have been found, which have been rarely reported before in literature. Some hypothesized explanations are given for the observed effects, which require future work to completely understand their underlying mechanisms.     

Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.     

Effects of textured morphology on the short circuit current of single crystalline silicon solar cells: Evaluation of alkaline wet-texture processes

The effect of different surface morphologies obtained by anisotropic etching on the light trapping and short circuit current of single crystalline silicon solar cells was investigated. The anisotropic texturing of a (1 0 0) silicon surface was performed using potassium hydroxide (KOH) solution and/or tetramethylammonium hydroxide (TMAH) solution including isopropyl alcohol (IPA) additive or tertiary butyl alcohol (TBA) additive. Texturing in TMAH solution formed smaller pyramids on the textured surface compared with texturing in KOH solution. Although the textured samples showed similar reflectances (except in the case of the TBA additive), they showed different short circuit currents. Texturing in KOH/TMAH solution led to a 9.6% increase in short circuit current compared with texturing in KOH/IPA solution, a typical etchant in commercial processes. Based on these results, the reflectivity has no simple proportionality relationship to the short circuit current, and the short circuit current of silicon solar cells should be the criterion used in evaluating texturing effects on reducing reflectance and forming a sound junction with high collection efficiency.     

Performance of hydrodynamic journal bearing under the combined influence of textured surface and journal misalignment: A numerical survey

A wisely chosen geometry of micro textures with the favorable relative motion of lubricated surfaces in contacts can enhance tribological characteristics. In this paper, a computational investigation related to the combined influence of bearing surface texturing and journal misalignment on the performances of hydrodynamic journal bearings is reported. To this end, a numerical analysis is performed to test three texture shapes: square “SQ”, cylindrical “CY”, and triangular “TR”, and shaft misalignment variation in angle and degree. The Reynolds equation of a thin viscous film is solved using a finite differences scheme and a mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. Preliminary results are compared with benchmark data and are consistent with a positive enhancement in misaligned bearing performances (load carrying capacity and friction). The results suggest that the micro-step bearing mechanism is a key parameter, where the micro-pressure recovery action present in dimples located at the second angular part of the bearing (from 180° to 360°) can compensate for the loss on performances caused by shaft misalignment, while the micro-pressure drop effect at the full film region causes poor performances. Considering the right arrangement of textures on the contact surface, their contours geometries can have a significant impact on the performance of misaligned journal bearings, particularly at high eccentricity ratios, high misalignment degrees and when the misalignment angle α approaches to $0\mathrm{°}$ or $180\mathrm{°}$.     

激光毛化轧辊技术的特色与进展

轧辊激光毛化技术的用途是什么? 什么样的轧辊需要毛化处理? 激光毛化轧辊技术 的优势是什么? 还存在什么不足? 激光毛化处理为什么能够延长轧辊的寿命? 激光毛化轧辊 改善了所轧钢板的哪些性能? 其机制是什么? 针对轧辊激光毛化技术的这几个基本问题 进行了讨论和释疑, 并指出了下一步的改进方向.     

Applying pulsed-laser holography to studying the filament behaviour during the air-jet texturing process

By means of a ruby laser, pulsed-laser holography—because of its high speed, non-destructive, and real-time properties—is introduced to the field of textile engineering for studying the behaviour of filaments emerging from a jet nozzle during the air-jet texturing process. It is proved that this is an efficient method to investigate the mechanism of the air-texturing process.     

TDPAC measurements in textured hcp samples

Time differential perturbed angular correlation measurements done on the 482 keV level of¹⁸¹Ta probe nuclei in well annealed reference foil samples ofα-ZrHf,α-TiHf andα-Hf indicate that all probe nuclei are defect free, substitutional and experience quadrupole frequencies characteristic of these matrices. But mostly the ratio of the intensities of the harmonic components of the quadrupole frequency is never in 3:2:1, which is understood to be due to the selective orientation of microcrystallites brought out by the pre thermo-mechanical treatments on the sample. This paper illustrates as to how texturing in general could cause ambiguities in the measurements of the hyperfine interaction parameters of probe nuclei particularly in hcp foil samples with or without the association of any defects and the ways to delineate the effect of texturing.