Fang Xuan, Wei Zhipeng, Chen Rui, Tang Jilong, Zhao Haifeng, Zhang Ligong, Zhao Dongxu, Fang Dan, Li Jinhua, Fang Fang, Chu Xueying, Wang Xiaohua
†State Key Laboratory of High Power Semiconductor Lasers, School of Science, Changchun University of Science and Technology, 7089 Wei-Xing Road, Changchun 130022, People's Republic of China.
‡Department of Electrical and Electronic Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055, People's Republic of China.
ACS Appl Mater Interfaces. 2015 May 20;7(19):10331-6. doi: 10.1021/acsami.5b01100. Epub 2015 May 7.
The structural and optical properties of ZnO and ZnO/ZnS core-shell nanowires grown by a wet chemical method are investigated. The near-bandgap ultraviolet (UV) emission of the ZnO nanowires was enhanced by four times after coating with ZnS. The enhanced emission was attributed to surface passivation of the ZnO nanowires and localized states introduced during ZnS growth. The emission of the ZnO and ZnO/ZnS core-shell nanowires was attributed to neutral donor-bound excitons and localized excitons, respectively. Localized states prevented excitons from diffusing to nonradiative recombination centers, so therefore contributed to the enhanced emission. Emission from the localized exciton was not sensitive to temperature, so emission from the ZnO/ZnS core-shell nanowires was more stable at higher temperature. UV photodetectors based on the ZnO and ZnO/ZnS core-shell nanowires were fabricated. Under UV excitation, the device based on the ZnO/ZnS core-shell nanowires exhibited a photocurrent approximately 40 times higher than that of the device based on the ZnO nanowires. The differing photoresponse of the detectors was consistent with the existence of surface passivation and localized states. This study provides a means for modifying the optical properties of ZnO materials, and demonstrates the potential of ZnO/ZnS core-shell nanowires in UV excitonic emission and detection.
研究了通过湿化学方法生长的ZnO和ZnO/ZnS核壳纳米线的结构和光学性质。用ZnS包覆后，ZnO纳米线的近带隙紫外（UV）发射增强了四倍。发射增强归因于ZnO纳米线的表面钝化以及ZnS生长过程中引入的局域态。ZnO和ZnO/ZnS核壳纳米线的发射分别归因于中性施主束缚激子和局域激子。局域态阻止激子扩散到非辐射复合中心，因此有助于发射增强。局域激子的发射对温度不敏感，因此ZnO/ZnS核壳纳米线在较高温度下的发射更稳定。制备了基于ZnO和ZnO/ZnS核壳纳米线的紫外光电探测器。在紫外激发下，基于ZnO/ZnS核壳纳米线的器件表现出的光电流比基于ZnO纳米线的器件高约40倍。探测器不同的光响应与表面钝化和局域态的存在一致。本研究提供了一种改变ZnO材料光学性质的方法，并证明了ZnO/ZnS核壳纳米线在紫外激子发射和检测方面的潜力。
