二维单层MoS₂半导体材料的制备及光电特性研究

Study of Preparation and Photoelectric Properties of Two-Dimensional Monolayer MoS₂ Semiconductor Materials

二维半导体材料是一类新兴的新材料,具有广泛的电学性能和潜在的应用价值。本文以S和MoO3粉末为原料,利用化学气相沉积法(Chemical Vapor Deposition, CVD),在SiO2/Si片上制备了高质量、大面积的单层MoS2单晶样品。利用XRD、OM、EDS、TEM、AFM及半导体光电特性分析设备,对不同制备样品的表面形貌、晶体结构、组成成份、样品厚度及光电特性进行了测试分析。结果发现,制备的三角形的单层及少层MoS2单晶主要呈现六角晶系结构,且边界清晰,表面光滑,有较好的透光性,最大尺度可达250 μm,MoS2单晶生长中的硫化反应过程符合VLS生长机制。在不同生长条件中,反应物中的S/MoO3的质量比和反应温度是影响单层MoS2单晶样品生长类型的主要影响因素。分析发现,制备单层MoS2单晶的最佳S/MoO3质量比为1000/30,而最佳沉积温度为900℃。测试发现,由单层MoS2单晶样品制备的光电器件具有很高的光电灵敏度和较好的光电响应特性。

Two-dimensional semiconducto materials are an emerging class of new materials with a wide range of electrical properties and potential practical applications. In this thesis, the high-quality and large-area monolayer MoS2 single crystal samples are directly synthesized on SiO2/Si substrates with chemical vapor deposition method while S and MoO3 powders were used as raw materials. the surface morphology, crystal microstructure, composition, thickness and photoelectric characteristics of the different MoS2 samples were analyzed by using XRD, OM, EDS, TEM, AFM and the semiconductor photoelectric characteristics analysis equipment, respectively. It is exhibited that the synthesized triangular monolayer and few layer MoS2 crystal samples are highly crystalline in hexagonal phases with the clear boundary, smooth surface and better light transmittance. and its maximum size of MoS2 crystal samples can reach 250 μm. The sulfurization mechanism in the MoS2 growth process is in accordance with the VLS growth mechanism. And the results showed the reaction temperature mass and ratio of S/MoO3 powder in the reactants are the main factors affecting the growth type and micro structure of the MoS2 samples in different preparing conditions. The research showed that the optimum S/MoO3 mass ratio for the fabrication of monolayer MoS2 single crystal is 1000/30, and the optimum deposition temperature is 900˚C. Meanwhile, we demonstrate ultrasensitive monolayer MoS2 photoelectric devices with the synthesized monolayer MoS2 crystal samples. And it appeared better photoelectric response characteristics.