黑磷光电特性及其异质结器件研究

发布时间：2018-06-12 23:05

本文选题：黑磷烯 + 二维纳米材料　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：黑磷作为一种新型的二维材料由于具有良好的电学与光电特性,因此受到科研工作者的广泛关注。黑磷属于双极性的窄带隙的半导体,其带隙为直接带隙,带隙类型不随着黑磷厚度的变化而改变;黑磷场效应管器件的载流子迁移率可以达到10000 cm2V-1s-1,略低于石墨烯的载流子迁移率但远高于过渡金属硫化物。此外,由于黑磷晶体结构的各向异性,在外场的作用下可以对黑磷的带隙在较宽的范围内进行调控,因此黑磷在柔性光电探测器件领域具有广阔的应用前景。现如今对于黑磷的研究尚处于初步阶段,对于黑磷的电学性质、力学性质以及相关的光电异质结器件的报道较少。本文针对以上的问题,采用扫描探针显微镜电学与力学模块配合半导体器件探针台对黑磷及其异质结的电学力学性质以及光电特性进行了研究,此外透射电镜以及微区拉曼光谱对于黑磷在退火条件下黑磷的相变行为进行了初步的探索。研究表明,原始黑磷的表面电势随黑磷厚度的增大逐渐降低,块状黑磷的表面电势约为-51.5 m V。此外,黑磷表面的磷氧化合物对于黑磷表面电势的影响较大。黑磷在300 oC退火过程中发生了黑磷表面磷氧化合物以及黑磷本身的挥发,此外还存在正交晶系的黑磷向单斜晶系的紫磷的相变过程。黑磷的相变过程导致了退火后黑磷表面电势的明显升高。退火处理后厚度为17.6 nm的紫磷为p型半导体,其空穴的载流子迁移率为226.3 cm2V-1s-1。本文利用扫描探针显微镜的力学模块对黑磷的力学性质进行了分析。黑磷存在明显的负泊松比材料的特性;而其杨氏模量随黑磷厚度的增加而逐渐降低。当黑磷的厚度为14.3 nm时,其杨氏模量为276±32.4 GPa。随着黑磷厚度的增加,其杨氏模量值趋近于块状黑磷的杨氏模量值。此外黑磷的断裂强度大于25GPa而断裂应变大于8%,满足柔性器件的要求。此外本课题利用横向力显微镜对黑磷表面摩擦力进行了初步的探索,相比于各向同性的Mo S2,黑磷的表面摩擦力存在着明显的各向异性。黑磷表面摩擦力最大值与最小值的方向呈90度角,对应黑磷的[100]与[010]晶向的各向异性。通过建立黑磷表面摩擦力与晶体取向的关系,对今后制备黑磷电学器件有一定的指导意义。利用导电原子力显微镜对B-P/Si异质结结构的光电特性进行了研究,B-P/p-Si异质结结构在光照的条件下,正向与负向均有光电流的产生,光电流的大小随着光照强度的提高而提高,在入射光波长为460 nm,功率为106 m W/cm2的光照条件下,光电流达到最大值约为11 n A。B-P/p-Si异质结结构对于460 nm波长的光照较为敏感,其光响应的大小可以达到4.5 A/W。而B-P/n-Si异质结结构的光电性能相比于B-P/p-Si性能较低,在正向偏压作用下,B-P/n-Si异质结结构出现明显的负微分效应。最后建立了B-P/Si异质结能带结构以及光生载流子分离规律。
[Abstract]:Black phosphorus, as a new two-dimensional material, is widely concerned by researchers because of its good electrical and photoelectric properties. Black phosphorus belongs to bipolar narrow band gap semiconductor, its band gap is direct band gap, the type of band gap does not change with the change of black phosphorus thickness. The carrier mobility of black phosphorus FET devices can reach 10000 cm2V-1s-1, which is slightly lower than that of graphene, but far higher than that of transition metal sulfides. In addition, due to the anisotropy of black phosphorus crystal structure, the band gap of black phosphorus can be adjusted in a wide range under the action of external field, so black phosphorus has a broad application prospect in the field of flexible photodetectors. At present, the study of black phosphorus is still in the preliminary stage. There are few reports on the electrical properties, mechanical properties and the related photovoltaic heterojunction devices of black phosphorus. In order to solve the above problems, the electrical and optical properties of black phosphorus and its heterojunction were studied by scanning probe microscope (SEM) and mechanical module combined with the semiconductor device probe bench. In addition, the phase transition behavior of black phosphorus under annealing condition was investigated by TEM and Raman spectroscopy. The results show that the surface potential of black phosphorus decreases with the increase of the thickness of black phosphorus, and the surface potential of bulk black phosphorus is about -51.5 MV. In addition, the surface potential of black phosphorus is greatly affected by phosphorus oxide compounds on the black phosphorus surface. The volatilization of phosphorus compounds on the surface of black phosphorus and black phosphorus itself occurs during the annealing of black phosphorus at 300oC. In addition, there is a phase transition process from black phosphorus of orthogonal crystal system to purple phosphorus of monoclinic system. The phase transition of black phosphorus leads to a significant increase in the surface potential of black phosphorus after annealing. After annealing, the thickness of purple phosphorus 17.6 nm is p-type semiconductor, and the carrier mobility of the hole is 226.3 cm2V-1s-1. In this paper, the mechanical properties of black phosphorus were analyzed by using the mechanical module of scanning probe microscope. Black phosphorus has the characteristic of negative Poisson's ratio, and its Young's modulus decreases with the increase of black phosphorus thickness. When the thickness of black phosphorus is 14.3 nm, its Young's modulus is 276 卤32.4 GPA. With the increase of the thickness of black phosphorus, the Young's modulus of black phosphorus tends to be similar to that of bulk black phosphorus. In addition, the breaking strength of black phosphorus is more than 25 GPA and the fracture strain is more than 8, which meets the requirements of flexible devices. In addition, the surface friction of black phosphorus is studied by transverse force microscope. Compared with the isotropic MoS _ 2, the surface friction of black phosphorus has obvious anisotropy. The direction of maximum and minimum friction force on black phosphorus surface is 90 degrees, which corresponds to the anisotropy of [100] and [010] directions of black phosphorus. By establishing the relationship between the surface friction of black phosphorus and the crystal orientation, it has a certain guiding significance for the preparation of black phosphorus electrical devices in the future. The optoelectronic properties of B-P / Si heterojunction structure were studied by means of conductive atomic force microscope (AFM). Under the condition of illumination, both positive and negative photocurrent were produced, and the photocurrent increased with the increase of light intensity. When the incident wavelength is 460 nm and the power is 106 MW / cm ~ 2, the maximum photocurrent is about 11nA.B-P / p-Si heterojunction, which is sensitive to the illumination at 460 nm, and the light response can reach 4.5 A / W. The optoelectronic properties of B-P / n-Si heterojunction are lower than that of B-P / p-Si, and the negative differential effect of B-P / n-Si heterojunction is obvious under positive bias. Finally, the band structure of B-P / Si heterojunction and the separation of photogenerated carriers are established.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ126.31

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