金属纳米颗粒包裹氧化锌微米线基电致波导发光器件研究

Zinc oxide (ZnO) microwires (MWs) based electroluminescent devices have important aspects. In order to realize electrically waveguide light-emitting devices, two tipical challenges and key scientific problems needed to be overcome, such as the suppression and adjustment of the surface defect modes of ZnO MWs, and the construction of hybrid waveguide structures along with the direction the ZnO MWs. So far, due to ZnO MWs metal-semiconductor-metal (MSM) structures, electrode contact properties, wavelength of the electroluminescent center, and emission region depend on the morphology and size of ZnO MWs. In consequence, the physical mechanism of electroluminescence is not clear and further investigation is expected. Meanwhile, while possessing natural resonant cavities, ZnO MWs are an ideal platform to design laser diodes, efficient light emitting devices (LED) and so on. But the gain area is restricted to the cross section. There is no relevant device structure, which can be used to modulate the resonant mode of photons confined within the cross section into the waveguide resonant modes along the length direction of ZnO MWs. This project aims at that, the characteristics of metal-semiconductor contact, the EL properties and emission mechanism of the device will be studied owing to the MSM structures, which will be designed based on bare ZnO MWs, and metal nanoparticles aggregation ccoated ZnO MWs, as well as electrically driven plasmon mediated non-radiative energy transfer between the surface defect modes of ZnO MWs and the localized surface plasmon modes of metal nanoparticles. This project also helps to further explore the modulation of surface defect states on account of metal nanoparticles aggregation, and the transport process of photons in the form of waveguide mode by means of surface plasmon wave, which excited by hybrid plasmonic waveguide nanostructures. Therefore, with the aid of this project, electrically induced waveguide light emitting devices can be achieved.

氧化锌（ZnO）微米线基电致发光器件在诸多方面有重要的应用前景，实现ZnO微米线基电致波导发光器件需要克服两个普遍难题和关键问题：抑制微米线表面缺陷态，构建沿着微米线长度方向的波导结构。目前单根ZnO微米线金属-半导体-金属（MSM）结构的电极接触属性、发光中心以及发光区域严重依赖于微米线形貌与尺寸，电致发光的机理还不够透彻；ZnO微米线具有天然微腔结构，增益区域受限于微米线的横截面，目前还没有相关器件结构能够实现将光子的谐振模式转化为沿着微米线长度方向的波导谐振模式。本项目基于单根ZnO微米线和金属纳米颗粒包裹的微米线MSM结构，研究器件的电极属性、发光来源，以及金属纳米颗粒表面等离子体介入下的非辐射能量转移过程，探索金属纳米颗粒聚集体对微米线表面缺陷态的调制，表面等离子体波调制光子的输运过程以实现将光子限域在沿着微米线长度方向的波导模式之中，有望实现基于单根微米线的电致波导发光器件。

本项目研究过程中，我们针对单根ZnO微米线以及超晶格微米线基可控性生长、n-型有效掺杂，单根微米线基高品质的光学谐振腔的构筑，单根微米线基荧光灯丝光源的构筑及其发光特征的调控，单根微米线异质结基发光二极管的构筑与调控研究等方面展开了研究。相应的研究结果分别发表在Small, Adv. Funct. Mater., ACS Photonics, Nanoscale，等国际刊物发表SCI论文19篇, 包括封面或封底报道论文4篇，培养6名博士获得学位。主要的进展与创新成果列举如下： .(1) 通过调控生长条件，实现了ZnO微米线横截面的可控性生长；在针对ZnO微米线电学特性的改性上，实现n-型ZnO微米线的有效掺杂，极大的调控ZnO微米线单根导电能力；此外，采用两步气相沉积合成方法可以实现超晶格结构微米线的生长，实现了光子的波导传输特性的调控。.(2) 基于单根Ga掺杂的ZnO微米线极大的增强了微米线的导电能力以及较高的结晶质量，可实现单根微米线类似于荧光灯丝发光的可见光灯丝光源，发光区局限于微米线的中间区域；通过改变微米线中Ga掺杂的浓度可进一步调控单根微米线荧光灯丝光源的发光中心波长，因此我们构筑一种新型的 “semiconducting emitters”。.(3) 通过旋涂或者溅射的方式在微米线表面制备一层金属纳米结构，可调控单根微米线荧光灯丝光源的发光特征，比如发光颜色和发光中心波长；该发光特征的调控来自于金属表面等离激元以非辐射形式衰减诱导的热电子再注入至微米线形成载流子的态填充所主导。.(4) 基于单根ZnO:Ga微米线和p-GaN衬底，我们制备了以近带边发光为主导型单根微米线异质结发光二极管，该能极大的抑制ZnO:Ga/p-GaN结区界面处的发光，将结区耗尽层限域在ZnO:Ga微米线中；随微米线中Ga元素含量的增加，可实现异质结二极管在紫外波段发光可调谐。.(5) 采用两步法气相沉积实验方法生长单根ZnO/ZnO:Ga超晶格微米线，这种微米线可用于构筑发光具有波导结构的荧光灯丝光源；且单根微米线异质结基发光二极管实现了激子-极化发光模式，发光具有一定的波导效应，实现了电驱动下波导电致发光器件.