原位生长宽禁带异质材料紫外探测器的研制
发布时间：2018-09-10 16:33
【摘要】：在当今这个科技快速发展的时代,探测技术存在于世界的各个角落,而紫外探测早已成为了一种兼具实用和发展前景的新探测技术。已广泛应用到火焰检测、天文探测、光波通信、成像技术以及光电集成电路等领域。研制一种低成本、响应度高、噪声电流低、响应速度快且探测灵敏度高的紫外光电探测器迫在眉睫。到目前为止,宽禁带半导体材料紫外探测器在低维度纳米材料的合成方面有较大优势。但是单一半导体材料的缺点较为明显,例如器件响应度受材料所限无法得到突破性提升,暗电流较大,响应恢复速度较慢等。近年来,人们通过各种方法来改善器件性能,其中制备复合材料形成异质结就是一种通过利用材料的能级差提高器件性能的有效方式。本论文利用一维二氧化钛(TiO_2)纳米材料作为基础,制备出钛酸锶(SrTiO_3)/TiO_2和钛酸钡(BaTiO_3)/TiO_2异质复合材料,并制作成紫外光电探测器。通过进行相关的表征和器件性能测试来深入探索其光电性能及工作原理。本论文首先采用低温极性水解法制备一维TiO_2纳米线阵列。通过SEM表征结果显示纳米线在FTO衬底上分布均匀、生长致密。竖直方向分叉明显,尖端无粘连,表现出一维半导体的形貌特征。其高比表面积和高载流子传输效率,为接下来制作高性能的异质结紫外光电探测器打下良好的基础。接下来通过二次水热原位生长法制备SrTiO_3/TiO_2异质结材料,其中作为第一步水热反应产物的TiO_2纳米线,将在第二步水热反应中同时充当异质结生长基底和原位生长的反应物,能有效减少杂质的掺入。异质结的生长过程基于奥斯特瓦尔德熟化效应,在保持材料一维结构特性的同时,将在纳米线之间形成网状结构,提高照光面积。复合材料表现出良好的紫外区域光谱吸收选择性,并且由于两种材料禁带宽度的差异,表现出光谱响应的蓝移特性,所以器件的光响应波长范围具有一定的可调性。对比SrTiO_3/TiO_2和单一TiO_2器件性能,异质结器件在光暗电流比、光响应度和恢复速度等参数上有较大突破,这归功于能级的差异促进光生载流子分离等效应,具体的机理分析将于文中详细给出。最后本论文将拓宽对原位生长异质结复合材料的研究,通过二次水热原位生长法制备BaTiO_3/TiO_2异质结材料,SEM表征结果显示异质结的生长将填充部分纳米线间的空隙,并且在不断增大前驱反应物量时,将会导致纳米线形貌被破坏。复合材料表现出较好的紫外区域光谱吸收选择性以及光谱响应的红移特性。基于BaTiO_3/TiO_2异质结的紫外光电探测器性能相对于单一的TiO_2器件会有所提升,这将在文中给出详细机理解释。本文制备了TiO_2纳米线阵列和两种基于TiO_2的异质结复合材料,并制作成器件应用于紫外探测领域。研制的器件在性能方面有较大的提升,文中对各项参数的变化都进行了深入探讨,这将为今后对紫外探测技术的研究打下良好的基础。
[Abstract]:Nowadays, with the rapid development of science and technology, detection technology exists in all corners of the world, and ultraviolet detection has already become a new detection technology with both practical and development prospects. UV photodetectors with high intensity, low noise current, fast response speed and high detection sensitivity are imminent. So far, wide band gap semiconductor UV detectors have great advantages in the synthesis of low-dimensional nanomaterials. In recent years, a variety of methods have been used to improve the performance of devices. Among them, the formation of heterojunctions by fabricating composite materials is an effective way to improve the performance of devices by utilizing the energy level difference of materials. Based on this, strontium titanate (SrTiO 3) / titanium dioxide (TiO 2) and barium titanate (BaTiO 3) / titanium dioxide (TiO 2) heterostructure composites were prepared and fabricated into ultraviolet photodetectors. The results show that the nanowires are uniformly distributed and densely grown on the FTO substrate. The vertical bifurcation is obvious and the tip is non-adhesive. The nanowires exhibit the morphological characteristics of one-dimensional semiconductor. SrTiO_3/TiO_2 heterojunction materials were prepared by thermal in-situ growth method. As the product of the first step hydrothermal reaction, TiO_2 nanowires will act as both the substrate for heterojunction growth and the reactant for in-situ growth in the second step hydrothermal reaction, which can effectively reduce the doping of impurities. Holding the one-dimensional structural characteristics of the materials, the nanowires will form a network structure between the nanowires to improve the illumination area. The composites show good spectral absorption selectivity in the ultraviolet region. Moreover, because of the difference of band gap between the two materials, they show blue shift characteristics of spectral response, so the wavelength range of optical response of the devices is certain. Compared with the performance of SrTiO_3/TiO_2 and single TiO_2 devices, the heterojunction devices have made great breakthroughs in the parameters of light-dark current ratio, light responsiveness and recovery speed, which is attributed to the difference of energy levels promoting the effect of photogenerated carrier separation. The detailed mechanism analysis will be given in this paper. Finally, the in-situ growth heterogeneity will be broadened. BaTiO_3/TiO_2 heterojunction materials were prepared by two-step hydrothermal in-situ growth method. SEM characterization showed that the growth of heterojunction would fill the gap between some nanowires, and the morphology of nanowires would be destroyed when the amount of precursor reactants increased. Absorption selectivity and red shift characteristics of spectral response. The performance of ultraviolet photodetectors based on BaTiO_3/TiO_2 heterojunctions will be improved compared with single TiO_2 devices. Detailed explanation of the mechanism will be given in this paper. In this paper, two nanowire arrays and two heterojunction composites based on TiO_2 have been prepared and fabricated and applied to devices. In the field of ultraviolet detection, the performance of the device has been greatly improved. Variations of various parameters are discussed in detail, which will lay a good foundation for the future research of ultraviolet detection technology.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN23
本文编号：2234999
[Abstract]:Nowadays, with the rapid development of science and technology, detection technology exists in all corners of the world, and ultraviolet detection has already become a new detection technology with both practical and development prospects. UV photodetectors with high intensity, low noise current, fast response speed and high detection sensitivity are imminent. So far, wide band gap semiconductor UV detectors have great advantages in the synthesis of low-dimensional nanomaterials. In recent years, a variety of methods have been used to improve the performance of devices. Among them, the formation of heterojunctions by fabricating composite materials is an effective way to improve the performance of devices by utilizing the energy level difference of materials. Based on this, strontium titanate (SrTiO 3) / titanium dioxide (TiO 2) and barium titanate (BaTiO 3) / titanium dioxide (TiO 2) heterostructure composites were prepared and fabricated into ultraviolet photodetectors. The results show that the nanowires are uniformly distributed and densely grown on the FTO substrate. The vertical bifurcation is obvious and the tip is non-adhesive. The nanowires exhibit the morphological characteristics of one-dimensional semiconductor. SrTiO_3/TiO_2 heterojunction materials were prepared by thermal in-situ growth method. As the product of the first step hydrothermal reaction, TiO_2 nanowires will act as both the substrate for heterojunction growth and the reactant for in-situ growth in the second step hydrothermal reaction, which can effectively reduce the doping of impurities. Holding the one-dimensional structural characteristics of the materials, the nanowires will form a network structure between the nanowires to improve the illumination area. The composites show good spectral absorption selectivity in the ultraviolet region. Moreover, because of the difference of band gap between the two materials, they show blue shift characteristics of spectral response, so the wavelength range of optical response of the devices is certain. Compared with the performance of SrTiO_3/TiO_2 and single TiO_2 devices, the heterojunction devices have made great breakthroughs in the parameters of light-dark current ratio, light responsiveness and recovery speed, which is attributed to the difference of energy levels promoting the effect of photogenerated carrier separation. The detailed mechanism analysis will be given in this paper. Finally, the in-situ growth heterogeneity will be broadened. BaTiO_3/TiO_2 heterojunction materials were prepared by two-step hydrothermal in-situ growth method. SEM characterization showed that the growth of heterojunction would fill the gap between some nanowires, and the morphology of nanowires would be destroyed when the amount of precursor reactants increased. Absorption selectivity and red shift characteristics of spectral response. The performance of ultraviolet photodetectors based on BaTiO_3/TiO_2 heterojunctions will be improved compared with single TiO_2 devices. Detailed explanation of the mechanism will be given in this paper. In this paper, two nanowire arrays and two heterojunction composites based on TiO_2 have been prepared and fabricated and applied to devices. In the field of ultraviolet detection, the performance of the device has been greatly improved. Variations of various parameters are discussed in detail, which will lay a good foundation for the future research of ultraviolet detection technology.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN23
【参考文献】
相关期刊论文 前1条
1 ;The ultraviolet photoconductive detector based on Al-doped ZnO thin film with fast response[J];Science China(Physics,Mechanics & Astronomy);2011年01期
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