表面等离激元增强ZnO基器件紫外电致发光研究

项目名称： 表面等离激元增强ZnO基器件紫外电致发光研究

项目编号： No.60876031

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 生物科学

项目作者： 张兴旺

作者单位： 中国科学院半导体研究所

项目金额： 36万元

中文摘要： ZnO基发光器件在信息、光通信、白光照明及及生物等领域具有广泛的应用前景，是当前半导体材料与器件研究的热点。由于ZnO本征缺陷，p型掺杂困难使得空穴浓度不高以及ZnO的自吸收等，使得目前ZnO基发光器件的发光效率普遍较低。本项目在n-ZnO/p-GaN异质结发光二极管（LEDs）中插入一宽带隙的AlN电子势垒层，AlN势垒层不仅将复合过程限制在n-ZnO一侧；且抑制了在ZnO高温生长过程中界面处GaOx非辐射复合中心的形成，增强了器件的电致发光强度。同时，在n-ZnO/AlN界面插入一层Ag纳米颗粒，利用ZnO中的激子与Ag局域态表面等离激元的耦合作用，加快ZnO近带边辐射跃迁速率，抑制缺陷复合发光及其它非辐射过程，使得器件的电致发光强度增大4.2倍。同时，我们通过氢等离子体处理，使器件电致发光强度提高3倍，且开启电压明显降低。综合这两种方法，我们可以将ZnO基LEDs的电致发光强度提高10倍以上。该项目实施后，发表SCI论文12篇，申请5项发明专利，获授权发明专利2项，培养研究生4名，一人获中科院优秀博士学位论文。本项目成果提供了一条解决ZnO及其它半导体材料低发光效率的可行途径。

中文关键词： 氧化锌；表面等离激元；电致发光；发光二极管

英文摘要： Recently, ZnO has attracted more and more attentions as an ultraviolet light-emitting material because of its potential applications in various fields, such as information technology, optical communications, and light illumination and so on. However, the efficiency of ZnO-based light emitting diodes (LEDs) was generally lower because of the following reasons, e.g., unavoidable intrinsic defects, the lower hole concentration and the light loss due to the ZnO self-absorption. In this project, a significant improvement of electroluminescence (EL) is observed when a 20 nm AlN intermediate layer is inserted into n-ZnO film/p-GaN LEDs. It can be ascribed to the suppression of the formation of the GaOx layer and confinement effect of the AlN potential barrier layer. We have prepared the surface plasmon (SP) enhanced n-ZnO/AlN/p-GaN LEDs by inserting the Ag nanoparticles (NPs) between the ZnO and AlN layers. The red-shift of EL emission peak and the reduced PL decay lifetime of ZnO confirmed the resonant coupling between excitons in ZnO and local SPs in Ag NPs, which will increase the ZnO band-edge recombination rate and suppress the defect and other non-radiative recombination processes. A maximum EL enhancement factor of 4.2 was observed for the SP-enhanced n-ZnO/AlN/p-GaN LEDs. The effects of H-plasma treatment on the EL of ZnO-based LEDs have been investigated systematically. It is found that after H-plasma treatment the EL intensity of the n-ZnO/AlN/p-GaN device is observed to be three times stronger than its as-grown counterpart under the same injection current, and the threshold voltage of the device is significantly reduced simultaneously. By the combination of SP coupling and H-plasma treatment, the EL intensity of the n-ZnO/AlN/p-GaN device can be enhanced by more than 10 times. Based on the results of this project, 12 articles has been published in refereed journals on physics and materials, 5 China patents has been applied for, and 2 patents have been authorized. These results provide an approach to overcome the low emission efficiency of ZnO and other semiconductor materials. This project is significant from the view of both fundamental research of plasmonics and applications of ZnO-based LEDs and laser diodes.

英文关键词： ZnO; surface plasmon; electroluminescence; light emitting diodes