Sahoo Anubhab, Miryala Muralidhar, Dixit Tejendra, Klimkowicz Alicja, Francis Bellarmine, Murakami Masato, Rao Mamidanna Sri Ramachandra, Krishnan Sivarama
Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India.
Superconducting Material Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-Ku, Tokyo 135-8546, Japan.
Nanomaterials (Basel). 2020 Jul 6;10(7):1326. doi: 10.3390/nano10071326.
The need for improved UV emitting luminescent materials underscored by applications in optical communications, sterilization and medical technologies is often addressed by wide bandgap semiconducting oxides. Among these, the Mg-doped ZnO system is of particular interest as it offers the opportunity to tune the UV emission by engineering its bandgap via doping control. However, both the doped system and its pristine congener, ZnO, suffer from being highly prone to parasitic defect level emissions, compromising their efficiency as light emitters in the ultraviolet region. Here, employing the process of femtosecond pulsed laser ablation in a liquid (fs-PLAL), we demonstrate the systematic control of enhanced UV-only emission in Mg-doped ZnO nanoparticles using both photoluminescence and cathodoluminescence spectroscopies. The ratio of luminescence intensities corresponding to near band edge emission to defect level emission was found to be six-times higher in Mg-doped ZnO nanoparticles as compared to pristine ZnO. Insights from UV-visible absorption and Raman analysis also reaffirm this defect suppression. This work provides a simple and effective single-step methodology to achieve UV-emission and mitigation of defect emissions in the Mg-doped ZnO system. This is a significant step forward in its deployment for UV emitting optoelectronic devices.
光学通信、杀菌及医疗技术等应用对性能更优的紫外线发光材料的需求，通常由宽带隙半导体氧化物来满足。其中，掺镁氧化锌体系尤为引人关注，因为通过掺杂控制来设计其带隙，有机会调节紫外线发射。然而，无论是掺杂体系还是其原始同类物氧化锌，都极易产生寄生缺陷能级发射，这损害了它们作为紫外线区域发光体的效率。在此，我们采用飞秒脉冲激光液相烧蚀（fs-PLAL）工艺，利用光致发光和阴极发光光谱，展示了对掺镁氧化锌纳米颗粒中仅增强的紫外线发射的系统控制。与原始氧化锌相比，掺镁氧化锌纳米颗粒中对应近带边发射与缺陷能级发射的发光强度之比高出五倍。紫外可见吸收和拉曼分析的结果也再次证实了这种缺陷抑制。这项工作提供了一种简单有效的单步方法，可在掺镁氧化锌体系中实现紫外线发射并减少缺陷发射。这是其在紫外线发光光电器件应用方面向前迈出的重要一步。
