退火温度对ZnO/SiO_2复合薄膜结构及光学性能的影响

采用溶胶-凝胶(sol-gel)法在玻璃衬底上制备ZnO/SiO2(ZSO)复合薄膜,并采用扫描电子显微镜(SEM)、X射线衍射(XRD)、紫外-可见分光光度计(UV-Vis)和光致发光(PL)谱对样品的形貌、晶体结构、透过率及光致发光性能进行表征.SEM结果表明,样品为双层结构,随着退火温度的升高,颗粒变大,并产生团聚现象;XRD结果表明,样品经退火处理后生成六方纤锌矿型ZnO,衍射峰强度和晶粒尺寸随退火温度的升高而增大;UV-Vis结果表明,样品同时具有ZnO和SiO2特征吸收边,双层复合薄膜中ZnO和SiO2两种不同材料的能带不连续导致360nm附近的曲线不平滑,并使能带蓝移,经400℃退火处理后的样品透过率较高;PL谱结果表明,在355nm波长激发下,样品分别在紫外区和蓝光区域产生发射峰,随着退火温度的升高,样品内缺陷密度减小,由缺陷引起的发光强度减弱.

Influences of Annealing Temperatures on Structure and Optical Properties of ZnO/SiO2Composite Thin Films

ZnO/SiO₂ (ZSO) composite thin films were deposited on glass substrates by means of sol|gel method. The microstructure, crystal structure, transmission and photoluminescent properties of the samples were characterized by SEM, XRD, UV|Vis and PL, respectively. The results of SEM show that double|layer structure can be observed clearly. The particles became larger as the annealing temperature rised and partly agglomerated. The results of XRD indicate that hexagonal wurtzite ZnO was formed after annealing, and with the annealing temperature rising, the peak intensity increased, while particle size also increased. The results of UV|Vis indicate that there were absorption edges for both ZnO and SiO₂. In double|layer composite thin films, the two different materials ZnO and SiO₂ caused curves near 360 nm to be unsmooth, and the edges to be blue shift at the same time. The samples have a higher transmittance having been annealed at 400 ℃. The PL spectra show that there were emission peaks in the ultraviolet region and blue region separately when the samples were excited at 355 nm. The photoluminescent intensity caused by defects weakened as the defects density reduced with the rising annealing temperature.