多晶硅表面金属催化化学腐蚀法制绒研究现状

在多晶硅太阳能电池的生产过程中, 金刚线切割技术(Diamond wire sawn, DWS)具有切割速度快、精度高、原材料损耗少等优点, 受到了广泛关注。金刚线切割多晶硅表面形成的损伤层较浅, 与传统的酸腐蚀制绒技术无法匹配, 金属催化化学腐蚀法应运而生。金属催化化学腐蚀法制绒具有操作简单、结构可控且易形成高深宽比的绒面等优点, 具有广阔的应用前景。本文总结了不同类型的金属催化剂在制绒过程中的腐蚀机理及其形成的绒面结构, 深入分析和讨论了具有代表性的银、铜的单一及复合催化腐蚀过程及绒面结构和电池片性能。最后对金刚线切割多晶硅片表面的金属催化化学腐蚀法存在的问题进行了分析, 并展望了未来的研究方向。     

醋酸铜辅助催化刻蚀制备金刚线切割多晶硅片绒面

金刚线切割多晶硅片表面减反射结构难以制备的问题阻碍着多晶硅光伏的进步.银辅助的酸腐蚀是解决这一问题的较好方法,但银的消耗和废液处理等增加了成本.本研究提出了醋酸铜辅助催化刻蚀金刚线切割多晶硅片方案,考察了刻蚀反应温度和时间对硅片表面形貌的影响,确定了最优的反应温度和时间分别为25℃和5 min.在此条件下,所获得的多晶...     

金刚线切割多晶硅片表面减反射绒面的制备

为解决金刚线切割多晶硅片表面制绒的问题,提出了一种创新的两步腐蚀制备硅表面陷光结构的方法。先以浓硫酸作为添加剂去除表面线痕,然后通过酸雾腐蚀法获得一种微米纳米复合的多孔陷光结构。样品在300～1100nm波长范围内的平均光反射率被降至8.6%,减反射效果优良,少子寿命提升0.6μs以上。此方法具有操作简单,无需复杂设备,成本低等优点,易实现工业化生产。     

银铜双原子MACE法制备多晶硅陷光结构及其性能的研究

采用一步银铜双原子金属辅助化学腐蚀(MACE)法,于室温下在多晶硅表面制备纳米陷光结构,研究了腐蚀时间及银铜摩尔比对多晶硅表面反射率和形貌的影响。用分光光度计测量了多晶硅表面的反射率,用扫描电镜观察了表面形貌。发现银铜双原子MACE法所形成的结构比银单原子或铜单原子MACE法所形成的结构更加平整且具有更低的表面反射率室温下经过银铜两种金属原子协同催化腐蚀后,在银铜原子摩尔比低于1/10时多晶硅表面形成了纳米多孔状与槽状结构共存的复合结构,在银铜原子摩尔比高于1/5时多晶硅表面形成密集的纳米线结构。研究结果表明,孔状与槽状的复合结构具有良好的陷光效果,当银铜原子摩尔比为1/10,腐蚀时间为180s时,多晶硅的反射率达到最低,仅为6.23%。     

利用金属辅助化学腐蚀法在硅表面获得纳米绒面结构以提升多晶硅太阳电池效率

在硅片表面制备绒面结构能够有效降低太阳光在硅片表面的反射损失,是提高太阳能电池转换效率的一条重要途径。通过真空热蒸发法在多晶硅片上沉积纳米银颗粒,利用金属辅助化学腐蚀(MACE)法,制备了不同腐蚀时间下的纳米绒面结构,其中,腐蚀时间为60s的纳米绒面的平均反射率低至4.66%(300~1100nm)。同时,对腐蚀时间为60s的纳米绒面用KOH溶液进行优化处理,将KOH处理前后的多晶硅片采用常规电池工艺进行电池制备研究。对比发现,经过KOH处理后的电池效率比未经KOH处理的电池效率提高了0.43%。     

金刚石线锯切割多晶硅片表面制绒工艺研究

晶体硅片的制绒技术是太阳能电池制造工艺中的关键步骤。本研究以工业中酸制绒方法为基础,研究了腐蚀时间、浓度对绒面结构以及反射率的影响。此外,还采用金属催化化学腐蚀法进行制绒,选用氢氟酸和硝酸银作为腐蚀液。而且对两种制绒方法效果进行了对比。研究获得的最优绒面结构及反射率结果的实验条件为:氢氟酸浓度4.6 mol/L、硝酸银浓度0.02 mol/L,室温下反应90 min,得到的平均反射率为8%,远低于目前多晶硅片制绒生产标准。     

金刚石线锯切割多晶硅片表面制绒工艺研

晶体硅片的制绒技术是太阳能电池制造工艺中的关键步骤。本研究以工业中酸制绒方法为基础, 研究了腐蚀时间、浓度对绒面结构以及反射率的影响。此外, 还采用金属催化化学腐蚀法进行制绒, 选用氢氟酸和硝酸银作为腐蚀液。而且对两种制绒方法效果进行了对比。研究获得的最优绒面结构及反射率结果的实验条件为: 氢氟酸浓度4.6 mol/L、硝酸银浓度0.02 mol/L, 室温下反应90 min, 得到的平均反射率为8%, 远低于目前多晶硅片制绒生产标准。     

一种太阳电池纳米陷光结构的制备方法

提出了一种利用石墨纳米颗粒作为掩膜,通过金属辅助刻蚀来制备具有低反射率的太阳电池纳米陷光结构的方法。用该方法制得了一种表面覆盖有纳米线和纳米孔的太阳电池纳米陷光结构。结合金属辅助刻蚀的机制和这种陷光结构的形成原理,分析了石墨纳米颗粒和H2O2浓度对陷光结构形貌的影响,并讨论了陷光结构的形貌对样品陷光性能的影响。最后,制得了在300～1100nm波长范围内平均反射率仅为3.6%的太阳电池陷光层。     

多晶硅太阳电池表面激光织构工艺研究

采用激光刻蚀,辅以化学溶液腐蚀对多晶硅片进行了表面织构.利用扫描电镜(SEM)、Helios LAB-rc反射率测试仪和Semilab WT2000少子寿命仪对样品进行了表征.结果表明,多晶硅表面经激光织构后表现出很好的陷光效果,反射率降低为8.0％.激光织构使硅片的少子寿命缩短,通过沉积Al2O3钝化薄膜可改善多晶硅片的电学性能.     

太阳能电池多晶硅表面激光制绒技术研究进展

太阳能作为一种绿色可持续的清洁能源，可以转化为热能或电能，是传统能源最重要的替代品。多晶硅太阳能电池由于具有较低的成本而被广泛用于光伏发电领域，降低多晶硅片表面反射率是提升多晶硅太阳能电池效率的重要手段之一。本文分析了硅基太阳能绒面微结构的吸光原理，梳理了各类常见制绒方法。在此基础之上，总结了激光制绒的各类加工方法，概括了不同激光加工方法对多晶硅片表面绒面产生的相应效果，其中，激光复合方法制绒的效果普遍优于单一激光制绒。随后从激光加工工艺的角度，分析了激光加工主要参数对绒面微结构形貌的影响：由于不同波长下多晶硅材料的吸收率不同，各加工效果亦不相同；通过调整脉冲激光加工中的重复频率、扫描速度等参数，可影响制绒面凹坑间距进而改变绒面微结构的密度，通过调整功率、单脉冲能量等因素则影响微结构的烧蚀程度或深度；而入射角度、能量分布及脉宽对制绒亦有明显效果。对比发现，各典型绒面微结构的形貌中，V形纹理比U形纹理更能有效地捕捉吸收光线，而二维复合型陷光微结构比单一型陷光微结构吸光性更好。在此基础之上，论述了化学后处理对提升多晶硅片绒面质量的作用体现，表明化学后处理能改善或消除多晶硅片经激光制绒后形成...     

硅熔体中碳化硅熔解与硅晶体中碳化硅生长

工业生产的太阳能电池用多晶硅锭内部常出现碳化硅夹杂,影响太阳能电池的转换效率,特别是严重威胁硅片的切割生产过程。本文研究了硅熔体中碳化硅熔解与硅晶体中碳化硅沉淀生长特性。在熔解实验中发现:即使在碳显著过饱和的情况下,碳化硅仍会熔解在1450℃的硅熔体中,同时熔体中易形核处发生新的碳化硅颗粒析出。在1350℃下进行了硅料中碳化硅沉淀的固相生长实验,结果表明晶体硅中碳化硅沉淀的高温固态生长十分缓慢。这一特性得到理论计算证实,它表明固相生长不可能是多晶硅锭中出现大颗粒碳化硅的原因。     

Tensile strain engineering of Si thin films using porous Si substrates

Highly tensile strained (up to 2.2%) thin monocrystalline silicon (mc-Si) films were fabricated by a simple and low-cost method based on the in-plane expansion of meso-porous silicon (PS) substrates upon low temperature oxidation. To control the film thickness below 100 nm, an original “two wafer” technique was employed during the porosification process. This method enables the fabrication of a 60 nm thick mc-Si films on 250 μm thick meso-porous silicon substrates over areas as large as 2 in. with a surface roughness and cleanliness comparable to that of standard Si wafers. Crack-free 60 nm thick Si films can be strained up to 1.2% by controlled low temperature oxidation of the PS substrate. Structural and strain analysis of the PS/mc-Si structures performed by transmission electron microscopy and micro-Raman scattering spectroscopy are reported.     

晶硅切割废料在碳化硅及其复合材料中的应用进展

光伏产业晶硅切割废料的传统回收工艺复杂且高纯硅的分离难度大、回收率低.而将废料提纯后直接制备碳化硅及其复合材料不仅方法简单、有效避开了硅难于分离的问题,且废料利用充分、制品多样化.从利用废料制备碳化硅粉体、碳化硅致密陶瓷、碳化硅多孔陶瓷、碳化硅/氮化硅复合材料、碳化硅基高温红外发射涂料以及碳化硅颗粒增强合金等方面综述了这一方向的研究进展,并基于该领域存在的一些主要问题,对未来的研究提出了几点建议.     

Study of polymorphous silicon as thermo-sensing film for infrared detectors

In this work we have deposited and characterized pm-Si:H thin films obtained by plasma deposition. Our aim is to use pm-Si:H as thermo-sensing element for infrared (IR) detectors based on un-cooled microbolometers. We have studied the electrical characteristics of pm-Si:H that are figures of merit important for IR detection, as activation energy, thermal coefficient of resistance (TCR), room temperature conductivity (σ_RT) and responsivity under IR radiation. The influence of the substrate temperature (200 °C and 300 °C) on the pm-Si:H characteristics has been also studied. Our results shown that pm-Si:H is an excellent candidate to be used as thermo-sensing film for microbolometers, due to its large activation energy and TCR, with an improved σ_RT.     

太阳能硅薄膜电池的研究进展

阐述了太阳能电池发电原理和硅系太阳能薄膜电池（单晶硅、多晶硅和非晶硅）的结构、基本原理和特点。介绍了硅系太阳能薄膜电池的发展现状,同时对其优缺点进行了比较,并分析了硅系太阳能薄膜电池的发展前景。     

多孔硅外延层转移制备SOI材料的研究

用多孔硅外延层转移的方法成功地制备出了SOI材料，卢瑟福背散射／沟道谱（RBS／C）和扩展电阻（SPR）的结果表明获得的SOI材料上层硅具有很好的单晶质量，电阻率分布均匀，上层硅与氧化硅埋层界面陡直。对制备多孔硅的衬底材料也作了研究，结果表明P型重掺杂的硅衬底在暗场下阳极氧化后仍保持很好的单晶性能，用超高真空电子束蒸发方法能外延出质量很好的单晶硅，并且，在一定浓度的HF／H2O2溶液中具有较高的腐蚀选择率，保证了上层硅厚度的均匀性。     

Hot-wire deposition of amorphous and microcrystalline silicon using different gas excitations by a coiled filament

Microcrystalline silicon (μc-Si:H) and amorphous silicon (a-Si:H) films were deposited using a hot-wire CVD (HWCVD) system that employs a coiled filament. Process gasses, H₂ and Si₂H₆, could be directed into the deposition chamber via different gas inlets, either through a coiled filament for efficient dissociation or into the chamber away from the filament, but near the substrates. We found that at low deposition pressure (e.g. 20 mTorr) the structure of the films depends on the way gases are introduced into the hot-wire chamber. However, at higher pressure (e.g. 50 mTorr), Raman measurement shows similar results for films deposited with different gas inlets.     

Fabrication of polycrystalline silicon thin films on glass substrates using fiber laser crystallization

Laser crystallization of amorphous silicon (a-Si), using a fiber laser of λ = 1064 nm wavelength, was investigated. a-Si films with 50 nm thickness deposited on glass were prepared by a plasma enhanced chemical vapor deposition. The infrared fundamental wave (λ = 1064 nm) is not absorbed by amorphous silicon (a-Si) films. Thus, different types of capping layers (a-CeO_x, a-SiN_x, and a-SiO_x) with a desired refractive index, n and thickness, d were deposited on the a-Si surface. Crystallization was a function of laser energy density, and was performed using a fiber laser. The structural properties of the crystallized films were measured via Raman spectra, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The relationship between film transmittance and crystallinity was discussed. As the laser energy density increased from 10-40 W, crystallinity increased from 0-90%. However, the higher laser density adversely affected surface roughness and uniformity of the grain size. We found that favorable crystallization and uniformity could be accomplished at the lower energy density of 30 W with a-SiO_x as the capping layer.     

Properties of reaction bonded silicon nitride obtained from slip cast preforms

Fabrication of silicon preforms of high green density (>1·2 g/cm³) by slip casting of silicon (in aqueous medium) has been studied. The nitridation product consists of 59–85% α-Si₃N₄, 7–22%β-Si₃N₄ and 7–23% Si₂N₂O phase. The amounts of un-nitrided silicon were negligible. The microstructure is either granular or consists of needle-like grains (α-Si₃N₄) and whiskers deposited in the large pores. MOR values of the specimens are almost constant up to 1000°C or 1400°C or show slight increase up to 1000°C or 1200°C. In some cases a little dip around 1200°C, then a sharp increase in MOR up to 1400°C was observed.K _ic values are almost constant up to 1000°C, and thereafter increase sharply. Pore size distribution, existence of Si₂N₂O phase and oxidation of RBSN at high temperatures have been considered for the explanation of the observed behaviour.