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离子注入及后退火方法制备SiO2基质中镶嵌ZnO纳米粒子的结构和光学性质
Structure and Optical Properties of ZnO Nanoparticles Embedded in SiO2 Prepared by Ion Implantation and Post-thermal Annealing
【摘要】 利用离子注入及后退火方法在光学纯的石英基片中注入 3× 10 17cm-2 剂量的Zn离子 ,然后在不同的退火条件下制备了高质量的镶嵌在SiO2 基质中的ZnO纳米粒子。X射线衍射光谱的实验结果表明 :在氧气气氛、70 0℃退火温度和 2小时退火时间条件下 ,得到了 (0 0 2 )择优取向镶嵌在SiO2 基质中的ZnO纳米粒子 ;而在 70 0℃退火温度、N2 和O2 气氛下顺次退火 1小时 ,得到了比上述条件 (0 0 2 )择优取向更好的ZnO纳米粒子。室温下对用上述两种条件制备的镶嵌在SiO2 基质中的ZnO纳米粒子观察到了自由激子吸收峰。室温光致发光谱中观察到了ZnO纳米粒子位于 3 2 9eV处的强紫外发射 ,紫外发射强度与深能级发光强度之比为4 0 ,紫外发射峰的半高宽为 96meV ,晶体质量类似于分子束外延方法生长的ZnO。在低温 (77K)光致发光谱中 ,较强的自由激子的紫外发光峰仍然存在
【Abstract】 ZnO is a versatile semiconductor material with hexagonal wurtzite structure and has a band gap of 3 3eV with a large exciton binding energy of 60meV at room temperature. ZnO has attracted much more interest in the field of the information and display like GaN due to the application of UV emission. In the past, the structure and optical properties of ZnO film has been investigated extensively, in contrast, it is less known about the structure and optical properties of ZnO nanoparticles embedded in dielectric matrix. By utilizing the wave guide structure of ZnO/SiO 2 and the optical properties of quantum dots, ZnO nanoparticles embedded in SiO 2 can decrease the intensity of the photon scattering and self absorption and increase the UV emission of ZnO nanoparticles. High quality ZnO nanoparticles embedded in SiO 2 was fabricated by zinc ion implantation (160keV, 3×10 17 cm -2 ) into optical grade silica substrate, followed by post thermal annealing. The dependence of the component, orientation, average grain size and the quality of ZnO nanoparticles on the annealing ambient and time was studied by X ray diffraction spectra. The zinc ion implantation with high dose and zinc atoms diffusion from silica surface can give rise to micro hole, weak bond and breaken bond in silica near the implantation layer. During the annealing process, the disappearance of micro hole and the reconstruction of weak and breaken bonds will occur. High quality ZnO nanoparticles embedded in SiO 2 was obtained as the annealing time increased to 2 hours at 700℃ in oxygen ambient. We can control the average grain size and density of ZnO nanoparticles by sequential post thermal annealing zinc implanted silica in nitrogen and oxygen ambient at 700℃. The average grain size of ZnO nanoparticles embedded in SiO 2 was in the range 18~26nm. The free exciton absorption and the UV emission of ZnO nanoparticles embedded in SiO 2 grown by post thermal annealing zinc implanted silica were observed by utilizing absorption spectra and micro photoluminescence spectra at room temperature. The experimental results indicated that the stress affected the free exciton absorption peak of ZnO nanoparticles. The oxygen atoms that diffused to silica inside can decrease the defects that located in the boundary of nanocrystalline ZnO and were induced by the ion implantation during the annealing process in oxygen ambient. The dependence of the intense UV emission of ZnO nanoparticles on the temperature indicated that the impurity containment in the sample is less. The intense UV emission of ZnO nanoparticles can be attributed to the free exciton emission of ZnO nanoparticles at room temperature. The relatively intense free exciton emission, the weak binding exciton and the free exciton replica emission of ZnO nanoparticles can be observed at 77K.
【Key words】 ion implantation; ZnO nanoparticles; thermal annealing; photoluminescence; exciton;
- 【文献出处】 发光学报 ,Chinese Journal of Luminescence , 编辑部邮箱 ,2002年05期
- 【分类号】O472.3
- 【被引频次】4
- 【下载频次】65