碳化硅纳米线的金属催化制备及性能研究

发布时间：2018-01-25 13:45

本文关键词： 碳化硅纳米线金属催化法超疏水性取向生长复合结构光电性能　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：碳化硅(SiC)因其特有的宽带隙、高温导电性、很高的击穿电压及杨氏模量等物理性能及极佳的抗氧化及腐蚀性和高温稳定性等特点受到了广泛研究。而碳化硅纳米线由于特有的一维尺寸,使其在碳化硅的优异性能的基础上,还获得了独特的电学、场发射、疏水性及机械性能等方面的性能。尽管研究人员已经在碳化硅纳米线的制备表征等方面进行了广泛的探讨并取得了一定的进展。但是由于其制备上困难还限制着碳化硅纳米线的广泛应用,目前还存在着制备温度高、光电及疏水性能认识不清楚,生长机制较缺乏等问题。针对上述问题,本文采用磁控溅射方法制备了非晶碳(a-C)和金属镍(Ni)作为制备碳化硅纳米线的前驱体,在相对较低的温度(900 oC)下获得了数量可观的高质量碳化硅纳米线:(1)研究了前驱体堆叠方式、制备温度、保温时间及冷却速度等因素与碳化硅纳米线的结构、成分和性能之间的关系;(2)利用掺杂Al元素制备了具有超疏水性的碳化硅纳米线/碳纳米管复合结构;(3)利用Ni-In合金作为催化金属制备了具有一定取向的碳化硅纳米线。利用非晶碳和金属镍制备的SiC纳米线呈立方结构,沿[111]方向生长并且有大量的层错产生。在纳米线顶端连接着催化金属颗粒,并且在纳米线及金属颗粒周围包裹着一层的非晶相。SiC纳米线的质量及产量与其生长条件密切相关:(1)不同的前驱体堆垛形式对碳化硅纳米线表面形貌有着重要影响;(2)升高制备温度不仅能增加碳化硅纳米线的产量,还能改善碳化硅纳米线的质量;(3)碳化硅纳米线的形成与前驱体中Ni和a-C的含量有着重要关系,当前驱体中Ni和a-C的含量适当时,才能形成产量可观的碳化硅纳米线;(4)冷却速度的升高不但可以提高碳化硅纳米线的纯度,还可以降低纳米线的直径,获得产量较高的极细碳化硅纳米线。讨论了纳米线缺陷对其光致发光性能的影响:纳米线中大量层错的产生,破坏了3C-SiC纳米线的原有的ABCBC……ABCBC堆垛次序,导致了一些尺寸微小的4H-SiC及6H-SiC片段产生。这种特有在3C-SiC纳米线基体上分布着大量4H-SiC及6H-SiC片段的结构导致了该纳米线具有多个发光峰位的出现:在紫外波段拥有一个位于357 nm的发光峰,除此以外,还在420 nm及535 nm处出现了另外两个发光峰。利用掺杂原理,在纳米线制备过程中掺入少量Al元素,实现了碳化硅纳米线及碳纳米管共生长,获得了碳化硅纳米线/碳纳米管复合薄膜。Al的含量和最终产物的形式密切相关:只有当Al的添加量为0.02g时,才能获得碳化硅纳米线/碳纳米管复合薄膜。纳米线及碳纳米管共生长的形成关键是Al元素的加入。该碳化硅纳米线/碳纳米管复合结构在未经任何表面处理下润湿角高达157o,具有优良的超疏水性。通过nano/micropillar复合结构模型对碳化硅纳米线/碳纳米管复合结构的润湿性进行了探讨:由于碳化硅纳米线与硅基底形成一定角度的空隙,使得该薄膜的疏水性较纯碳纳米线大幅提高。此外,该复合结构还具有较好的自清洁性和化学稳定性。通过在制备过程中添加In元素,可以获得具有一定取向的碳化硅纳米线阵列。结果表明碳化硅纳米线在Ni-In合金的催化作用下,在硅(100)基底上形成了低密度的沿着某些特定方向生长的碳化硅纳米线。研究了定向生长和光致发光性能的内在联系。结果表明:相对于无明显取向的碳化硅纳米线,定向生长的碳化硅纳米线的光致发光性能得到了明显提高,具有峰强更高,发光峰位更明显的特点。利用场效应晶体管研究了SiC纳米线的电学性能,结果表明:SiC纳米线为n型半导体且当Vds为0.5 V时,该器件的载流子迁移率为12.9 cm2/V·s。采用a-C和Ni作为前驱体制备的SiC纳米线具有制备温度低,产量大等特点。利用掺杂原理可以获得具有超疏水性的碳化硅纳米线/碳纳米管复合结构及具有一定取向的碳化硅纳米线,因此金属催化法适合用作生产产量可观、性能可控、高质量的碳化硅纳米线。
[Abstract]:Silicon carbide (SiC) because of its wide band gap, high breakdown voltage and electrical conductivity, Young's modulus and excellent physical properties such as high oxidation resistance and corrosion resistance and high temperature stability and other characteristics have been widely studied. The SiC nanowires as one-dimensional size specific, which based on the excellent properties of silicon carbide. Also won the unique electrical, field emission, hydrophobic properties and mechanical properties. Although researchers have in the preparation and characterization of silicon carbide nanowires were widely discussed and made some progress. But because of its wide application on the preparation difficulty also restrict SiC nanowires, at present there are prepared by high temperature, photoelectric and hydrophobic properties of unclear problems, lack of growth mechanism. In order to solve the above problems, this paper amorphous carbon prepared by magnetron sputtering method (a-C) and nickel (N I) as the precursor for preparation of SiC nanowires, at relatively low temperatures (900 oC) to obtain high quality silicon carbide nanowires: a considerable number (1) of stacked precursor, preparation temperature, holding time and cooling rate structure factors and the relationship between SiC nanowires. The composition and performance; (2) with silicon carbide nanowires / super hydrophobic carbon nanotube composite structure were prepared by doping Al system; (3) using Ni-In alloy as the catalytic metal preparation of SiC nanowires with certain orientation. The use of amorphous carbon and metal nickel prepared SiC nanowires are cubic the structure, growth along the [111] direction and there are a lot of fault. On top of the nanowire connected with the catalytic metal particles, and around nanowires and metal particles wrapped in a layer of amorphous phase.SiC nanowires yield and quality and growth conditions are closely related : (1) the precursor of stacking different forms have important influence on the surface morphology of SiC nanowires; (2) increasing preparation temperature can not only increase the yield of SiC nanowires, can improve the quality of silicon carbide nanowires; (3) the contents of Ni and a-C formation and the precursor of silicon carbide nanowires in a an important relationship between Ni and a-C, the content of the current drive in the appropriate time, in order to form silicon carbide nanowires yield considerable; (4) the increase of the cooling rate can not only improve the purity of silicon carbide nanowires, but also can reduce the diameter of the nanowires, fine SiC nanowires obtained higher yield. The influences of light line defect influence on the photoluminescence properties of the nanowires in large number of faults have destroyed the original ABCBC.ABCBC 3C-SiC nanowires stacking sequence leads to some small size, 4H-SiC and 6H-SiC. This kind of special fragment in 3C-SiC nanowires The matrix structure of the distribution of a large number of 4H-SiC and 6H-SiC fragment resulted in the nanowires with multiple emission peaks located at 357 nm: with a peak in the ultraviolet range, in addition, in 420 nm and 535 nm at two other peaks. By doping a small amount of Al principle. Doped nanowires in the preparation process, the silicon carbide nanowires and carbon nanotubes were grown, obtained SiC nanowires / carbon nanotube composite film is closely related to the content of.Al and the final product form: only when the Al content is 0.02g, in order to obtain SiC nanowires / carbon nanotube composite film. The formation of nanowires and carbon nanotubes were grown is the key elements of Al. The SiC nanowires / carbon nanotube composite structure without any surface treatment under the wetting angle of up to 157o, with excellent super hydrophobic. By nano /micro Pillar composite structure model of SiC nanowires / nanotubes wettability of composite structure are discussed: the gap of silicon carbide nanowires and the silicon substrate to form a certain angle due to the hydrophobicity of the film, which is pure carbon nanowires significantly improved. In addition, the composite structure has good self-cleaning property and chemical stability through. The addition of In element in the preparation process, it has certain orientation silicon carbide nanowires arrays were obtained. The results show that the catalytic effect of SiC nanowires in Ni-In alloy, the silicon (100) substrate to form a low density along with SiC nanowire growth. Some specific directions of directional growth and light induced intrinsic contact the electroluminescent properties. The results showed that compared with silicon carbide nanowires without obvious orientation and directional growth of SiC nanowires photoluminescence properties were improved, with Feng Qiang Higher emission peak more obvious characteristics. The results showed that the electrical properties of SiC nanowires was studied, using field effect transistor: SiC nanowires are n type semiconductor and when Vds is 0.5 V, carrier mobility of the devices is SiC cm2/V S. 12.9 nanowires using a-C and Ni as the precursor preparation with low preparation temperature, large output characteristics. With SiC nanowires / super hydrophobic carbon nanotube composite structure and has a certain orientation of silicon carbide nanowires can be doped by metal catalysis principle, therefore suitable for the production of significant production, controllable performance, SiC nanowires with high quality.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;TQ163.4

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