氮化硅纳米线的可控掺杂、能带结构及其光致发光性能研究

Silicon nitride (Si3N4) nanowires are one of the typical "structural-functional integral" broadband semiconductor materials, which have some superior properties, such as high strength, high modulus, high temperature resistance, oxidation resistance, radiation resistance, etc. Moreover, their photoluminescence properties could be controlled by changing the band structure in order to fulfill the requirements for electro-optic technology applications. The current project is going to explore the new processing technology and dimensionality control method for Si3N4 nanowires via nitriding the cryomilled high purity silicon powders; to establish the doping control methods for Si3N4 nanowires, with doping elements selected in the order of valence electron at different blocks in the periodic table; to reveal the growth mechanisms of Si3N4 nanowires by studying the phase compositions and microstructure evolution during the nanocrystalline and nitriding process; to clear the relationship between band structure (especially the imperfection level, doping level, bandgap) and photoluminescence properties, combining the photoluminescence properties test and calculation of the Si3N4 nanowires band structure by the first principle method; finally to reveal the photoluminescence mechanisms of the Si3N4 nanowires with controlled dimensionality and doping elements.The predicted achievements of the project will supply technical support and theoretical basis for control and optimization of photoluminescence properties of Si3N4 nanowires.

氮化硅纳米线具备高比强、高比模、耐高温、抗氧化、抗辐射等特性，是一种典型的"结构-功能一体化"宽禁带半导体材料，通过能带结构可以调控其光致发光性能以满足不同光电应用要求。本项目致力于建立低温球磨、高温氮化制备氮化硅纳米线的制备新技术和尺度控制方法；根据元素周期表中不同价电子排布分区选取掺杂元素并控制掺杂含量，建立氮化硅纳米线可控掺杂技术；通过研究纳米晶化过程、氮化过程的物相组成和微观结构演变，揭示氮化硅纳米线的生长机理；结合氮化硅纳米线光致发光性能的测试与其能带结构的第一性原理计算，阐明氮化硅纳米线的能带结构，特别是缺陷能级、杂质能级、禁带宽度与光致发光性能之间的关联，揭示尺度、掺杂可控的氮化硅纳米线的光致发光机理，为氮化硅纳米线的发光性能调控与优化以及光电应用提供技术支撑和理论依据。

项目以寻找单晶氮化硅纳米线合成制备新技术和揭示氮化硅纳米线光致发光性能机理为研究重点，采用液氮低温球磨技术获得不同晶粒尺寸的纳米晶硅粉，再通过1200-1500oC氮气气氛处理，实现了高纯氮化硅纳米线以及可控掺杂氮化硅纳米线的高效制备，掌握了纳米线的尺度和掺杂含量等关键控制技术。项目结合实验测试表征和第一性原理计算模拟，研究了本征缺陷、掺杂等与氮化硅晶体结构、能带结构之间的关联关系，阐明了缺陷能级对氮化硅纳米线光致发光性能的影响机理。项目研究发现，不同价电子结构元素掺杂的氮化硅纳米线的发光性能不同，通过引入不同的掺杂元素实现了氮化硅纳米线光致发光性能的有效调控。项目为氮化硅纳米线的合成制备提供了新技术，为其光致发光性能的调控与优化提供了实验和理论依据。