稀土Tb3+掺杂纳米ZnO的发光性质

ZnO是一种优良的直接宽带隙半导体发光材料(Eg=3.4 eV),具有优异的晶格、光学和电学性质,稀土离子掺杂浓度和热处理温度对ZnO∶Re3 纳米晶发光强度、峰位变化等光学性质具有重要影响.利用溶胶-凝胶法(Sol-Gel),在不同退火温度下,制备了不同浓度的ZnO∶Tb3 纳米晶.室温下,测量了样品的X射线衍射谱(XRD)、光致发光谱(PL)和激发谱(PLE).观察到纳米ZnO基质在520 nm附近宽的绿光可见发射和稀土Tb3 在485,544,584和620 nm附近的特征发射.通过ZnO基质可见发射强度和稀土Tb3 特征发射强度随Tb3 掺杂浓度、退火温度的变化关系,获得了5D4→7F5跃迁的绿色主发射峰最强的样品制备工艺参数,其退火温度为600℃、掺杂浓度为4 at%;给出了稀土Tb3 的激发态5D4→7F6(485 nm),5D4→7F5(544 nm)和5D4→7F4(584 nm)的发射机制;证实了稀土Tb3 与纳米ZnO基质之间存在双向能量传递.

Luminescence Characteristics of Terbium-Doped Nanocrystalline Zinc Oxide

It is known that zinc oxide is a kind of important functional and novel material of II-VI wide bandgap semiconductor (Eg = 3.37 eV), and has excellent microstructural, chemical and physical properties. The intensity of photoluminescence, luminescence peak positions and other kinds of luminescence properties of ZnO : RE3+ nanocrystalline are strongly dependent on the annealing temperature and time, and the concentration of the doping rare earth ions. Terbium-doped zinc oxide nanocrystalline were successfully prepared by sol-gel process at different annealing temperature. Photoluminescence spectrum (PL), photoluminescence spectrum excitation(PLE) and X-ray diffraction pattern(XRD) of nanocrystalline ZnO : Tb3+ with excitation wavelength 368 nm were measured at room temperature. The emission from 5D4-->7F6 (485 nm), 5D4-->7F5 (544 nm), 5D4-->7F4 (584 nm) and 5D4-->7F3 (620 nm) of Tb3+ ions, and the wide visible band of ZnO were observed. Photoluminescence intensity of nanocrystalline ZnO : Tb3+ on the doping concentration and annealing temperature was given, and it was found that the optimal dopant concentration and annealing temperature were 4 at% and 600 degrees C, respectively. The luminescence process of Tb3+-doped zinc oxide nanocrystalline was investigated by using PL and XRD. The photoluminescence mechanism suggests that there is energy transfer between ZnO nanocrystalline hosts and the doping Tb3+ centers.