Ag离子注入ZnO薄膜对其发光性质的影响

Effect on ZnO thin film photoluminescence after Ag ion implantation

采用磁控溅射技术在蓝宝石基底上制备了Zn O薄膜,并对样品在氧气氛下进行了热处理,然后采用不同能量、剂量的Ag离子注入Zn O薄膜中,形成Ag纳米颗粒。利用X射线衍射、光致发光、紫外可见吸收等技术详细地研究了样品的结构与发光性质。结果表明,未注入的Zn O薄膜在380 nm和610 nm处出现发光峰,分别对应Zn O激子峰与深能级缺陷峰。Ag离子注入Zn O样品的激子发光峰增强,并在400 nm和430 nm左右处出现新发光峰,同时深能级缺陷引起的发光峰减弱。在N2气氛下退火处理后,Ag离子注入Zn O样品在400 nm处的发光峰消失,430 nm左右发光峰减弱。Ag离子注入Zn O薄膜中合成了Ag纳米颗粒,观察到了Ag纳米颗粒的等离子共振效应。对Ag纳米颗粒和离子注入产生的缺陷、Zn O发光性质的影响给出了解释。

Background： Zinc oxide has an extensive applied prospect on photoelectric devices, like light-emitting diodes and solar cells, due to its 3.37 eV optical band gap and 60 meV excition binding energy. Recently, doping ZnO with metal elements has become a popular research topic because of the dramatic improvement on photoelectricity, piezoelectric property and conductivity. Comparing with other elements, Ag is appropriate to act as acceptor dopant element because it has a shallow acceptor level in ZnO. Therefore, many coupling systems of ZnO-Ag nanostructures have been researched. Purpose： Various methods of incorporating Ag and ZnO have been researched but it is hard to control the uniformity of doped Ag in ZnO. The quality of ZnO thin films is also one of the key factors affecting the property of samples. This paper mainly focused on how to prepare high-quality ZnO thin films by magnetron sputtering technique and how to improve the photoluminescence property of ZnO via controlling the uniformity of Ag dopant. Methods： High-quality ZnO thin films were deposited on A1203 substrates by magnetron sputtering technique with combination of subsequent thermal annealing. The films were then implanted with Ag ions at different energies and fluences. We discussed the structural and photoluminescence properties of implanted ZnO thin film by means of grazing incidence X-ray diffraction （GIXRD）, photoluminescence （PL）, UV-vis and scanning electron microscope （SEM）. Results： The PL of prepared samples showed that two bands at 380 nm and 610 nm were observed for pure ZnO films and two new peaks at 400 nm and 430 nm appeared for the implanted ZnO. Ag ion implantation strongly enhanced the excition peak of ZnO and quenched the PL peak from oxygen defect of ZnO. However, the PL bands of implanted ZnO films at 400 nm and 430 nm have been quenched after thermal annealing at nitrogen atmosphere. Conclusion： In summary, Ag nanoparticles were formed in ZnO thin films after Ag ion implantation. Thus the surface plasma resonance absorption peak from Ag nanoparticles was observed. Furthermore, the formed Ag nanoparticles quenched the oxygen defect and enhanced the excition peak of ZnO. The existence of Agz, and Agi energy levels and synthesis ofAg nanoparticles made a great improvement on the PL property of ZnO.