Zinc oxide nanoparticles fabricated by ion implantation and thermal oxidation and the optical properties

本研究包括三个子主题，即(1)ZnO纳米颗粒（NPs）的形成过程，(2)高密度激发对ZnO NPs的影响，以及(3)ZnO NPs尺寸控制的尝试。(1)通过60kev的Zn+离子注入，在石英玻璃样品中形成ZnO NPsZn NPs的形成过程。然后将含Zn NPs的样品在氧气中退火，将Zn NPs氧化为ZnO NPs。从Zn NPs到ZnO NPs的转变通过。紫外-可见吸收光谱，掠射角入射x射线衍射，截面透射电子显微镜，卢瑟福后向散射光谱。其中一个引人注目的结果是，在二氧化硅玻璃内部形成的Zn NPs向玻璃表面移动，并在玻璃表面转化为ZnO NPs。(2)高密度激发对ZnO NPs的影响首先，利用氮激光的时间分辨光致发光测量系统对ZnO NPs进行了光致发光测量，但灵敏度太低，无法检测样品的光致发光。我们利用YAG激光器和ICCD探测器建立了一个新的测量系统，成功地观测了高密度脉冲激光激发下的PL光谱。激子PL在室温下表现出饱和的激发强度依赖关系。(3) ZnO NPs尺寸控制的尝试。研究了通过改变通量对Zn和ZnO纳米粒子粒径的控制。在注入态下，锌纳米粒子的平均尺寸随着5 ~ 10×10^<16 b> ions/cm2的影响而增大。在10×10^<16 b> ions/cm2以上，由于表面溅射，平均尺寸表现出饱和行为。氧化退火后，注入到2×10^<16 b> ions/cm2以下的样品主要转变为Zn_2SiO_4相，而不是ZnO NPs。

This study consists of three sub-themes, i.e., (1) Formation processes of ZnO nanoparticles (NPs), (2) High density excitation effects on ZnO NPs, and (3) an attempt for size control of ZnO NPs.(1) Formation processes of ZnO NPsZn NPs were formed in silica glass samples by Zn+ ion implantation of 60 keV. After then the samples including Zn NPs were annealed in oxygen gas to oxidize the Zn NPs to ZnO NPs. The transformation from Zn NPs to ZnO NPs was evaluated by. UV-Vis optical absorption spectroscopy, glancing angle incident x-ray diffraction, cross-sectional transmission electron microscopy, Rutherford backscattering spectrometry. One of the striking results is that Zn NPs formed inside the silica glass move toward the surface of the glass and transform to ZnO NPs on the surface of the glass.(2) High density excitation effects on ZnO NPsFirst, photoluminescence (PL) measurements of ZnO NPs using a time-resolved PL measurement system using a nitrogen laser was carried out, but the sensitivity was too low to detect PL of our samples. We have built a new measurement system using YAG laser and ICCD detector, and succeeded in the observation of PL spectra under high-density pulsed laser excitation. The exciton PL showed a saturated excitation intensity dependence at room temperature.(3) An attempt for size control of ZnO NPs.Size control of Zn and ZnO NPs by changing the fluence was examined. In as-implanted state, the average size of Zn NPs increases with the fluence between 5 and 10×10^<16>ions/cm2. Above 10×10^<16>ions/cm2, the average size showed a saturation behavior due to surface sputtering. After the oxidation annealing, the samples implanted to 2×10^<16>ions/cm2 or less mainly transformed to Zn_2SiO_4 phase instead of ZnO NPs.