窄带隙半导体SnE(E=S, Se)低维结构的气相可控生长与物性研究

Narrow band-gap semiconductors SnE(E=S, Se) with typical layered crystalline structure are environment- friend optoelectronic and thermoelectric materials with excellent performance, and also a class of newly emerging two-dimensional (2D) materials. To date, there has been few research on the growth and properties of SnE low-dimensional (LD) structures. The project is focused on SnE LD structures with diverse dimensionalities grown by chemical vapor deposition or vacuum thermal evaporation. The growth mechanism of SnE one-dimensional (1D) and 2D structures will be systematically studied and the synergistic effects of inherent crystal structures and the oriented growth factors involved in the vapor-phase growth systems will be deeply studied. The effective technology will be developed to achieve the controlled growth of SnE LD structures with diverse dimensionalities. The dependence of optoelectronic properties on some key parameters of materials, including dimensionalities, sizes, compositions, surfaces, etc., will be examined in details to reveal the relation between the properties and structures. The infrared photodetecting, optical waveguiding and lasering performance of the SnE LD structures will be checked. Aiming on the applications, the research on the doped, ternary alloyed as well as heterostructured SnE LD structures will carried out, and the changes in their band structures and optoelectronic properties will be studied, which would enable us to tune properties and promote performance of the materials. It is believed that the results of the project will broaden and deepen our knowledge on SnE LD structures, as well as benefit the research on the controlled growth and property-tuning of other layered materials.

窄带隙半导体SnE(E=S,Se)具有典型的层状晶体结构，是环境友好的高性能光电和热电材料，也是新兴的二维材料体系，其低维结构的生长调控与物性研究目前还很缺乏。本项目拟以SnE低维结构为研究对象，采用化学气相沉积和真空热蒸发镀膜两种气相生长方法，系统研究其一维和二维生长规律，了解其晶体结构与气相系统取向生长因素的作用关系，发展有效的实验技术，实现多种维度可控生长；利用结构、光学、电学多种物化表征手段，系统研究材料的维度、尺寸、组分、表面等关键参数对其光电性质的影响，分析其红外波段的光电探测、光波导、受激辐射等光电性能，掌握其结构物性关系；以功能应用为导向，开展SnE低维结构的掺杂、三元合金化以及异质结生长研究，考察其能带结构与光电性质的变化规律，对材料实现物性调控和性能提升。项目的开展，将丰富和深化SnE低维结构的研究，同时为其它层状结构材料的多维度生长和物性调控提供有益的借鉴。

层状晶体结构的窄带隙半导体SnE(E=S,Se)是环境友好的传统光电材料和新兴的高性能热电材料，其低维结构的生长调控与物性研究具有重要的科技价值。本项目针对不同维度和尺寸的SnE低维结构在气相体系中生长的规律，及其结构物性开展了系统深入研究，取得了一些重要进展。主要研究内容及结果包括：（1）无催化剂生长SnSe一维纳米线及物性研究。利用化学气相沉积法，首次实现了超长SnSe单晶纳米线的无催化剂生长,获得了高质量的SnSe单晶纳米线，长度可达毫米级，长径比可达3000，结晶良好。提出了一维自发取向生长气固机制解释纳米线的生长；SnSe单晶纳米线显示出较好可见光和近红外光吸收能力，具有一定的光电转化应用潜力。（2）二维SnSe单晶纳米片的生长及物性研究。通过调整生长参数从而改变纳米结构的生长行为，实现了二维SnSe单晶纳米片的不依赖衬底生长。其生长与衬底没有外延匹配关系，是材料层状晶体结构驱动的自发二维生长。（3）SnSe1-xSx三元合金单晶纳米片的生长及物性研究。实现了单晶纳米片从SnSe到SnS全范围的组分调控，同时保持了良好的结晶和规则外形,光学带隙得到了有效调控（4）利用真空热蒸发法生长SnSe纳米片阵列膜，实现了膜的形貌调控，可以在绝缘、导电以及柔性衬底上生长，为其功能化应用提供了良好基础。（5）生长得到了新型SnS/SiOx核壳结构纳米线，提出了自束缚的气-液-固(VLS)机制来解释其生长。（6）SnSe单晶纳米带的生长及热电性质。利用溶剂热法生长了SnSe高质量单晶纳米带，研究了纳米带的结构及热电性质，发现其纳米块体热电优值比普通多晶SnSe粉体提高了约60%。(7)制备了新型SnSe/Bi2Se3纳米片异质结，对其结构进行了表征分析。.以上研究成果发展了多种维度SnE纳米结构的可控生长技术，获得了一些新型纳米材料，了解了这些材料的生长规律以及光电热电性质，为其应用发展奠定了良好的研究基础。

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