两步溶液法制备亚微米ZnO棒阵列及其退火后的发光

通过改变溶液浓度、酸碱度等生长条件,用两步化学溶液沉积法在玻璃衬底上制备出有序排列的亚微米级ZnO棒阵列,棒的截面呈正六边形,直径约为200~500nm。测量了样品的XRD谱和扫描电镜像,证明这些样品都是六方纤锌矿结构的ZnO单晶,且以[002]方向择优生长。将样品退火前后的PL光谱进行比较分析,发现退火后样品的发射光谱中紫外峰消失而长波段的红色发光峰红移并且增强(峰位由630nm左右移到720nm),而其激发光谱中的室温激子激发峰也增强。当退火时间增加到6h后,出现了由430nm的蓝峰和505nm绿峰组成的宽谱带蓝绿色发射。并对发光机理进行了讨论。

Luminescent Properties After Annealing of Arrayed ZnO Sub-microrods Prepared by Two-step Chemical Solution Deposition

ZnO materials are very promising for applications in field emission displays and photonic devices operating in blue and UV spectral ranges due to its wide band gap(3.37 eV) and large exciton binding energy(60 meV).Therefore,fabrication and properties of ZnO materials have attracted considerable attention.In this work,arrayed ZnO hexagonal sub-microrods have been synthesized onto glass substrates through a simple two-step chemical solution deposition by altering pH,the concentration of solution and other factors.XRD patterns,SEM images have been measured,which reveals almost of the ZnO microrods were highly orientated on thin films of ZnO template on the glass substrate and grown along the(002) direction.The diameter of the rods is in the range of 200~500 nm and the length of the rods is about several micro-meters.XRD patterns showed that the crystal structure of most of the ZnO sub-microrods is hexagonal structure.The luminescent properties of the ZnO sub-microrods which annealed at 650℃ with different time was investigated by excitation spectrum and photoluminescent spectrum.It revealed the excitation spectra of ZnO sub-microrods have a strong exciton excitation peak at 380 nm,and the blue default emission of the photoluminescent spectra have a blue-shift from 452 nm to 440 nm,the wide orange-red default emission intensity of the photoluminescent spectra become stronger with the peak red-shift from 630 nm to 720 nm with the annealing time increases.The PL spectra of ZnO have a blue peak at 430 nm and a green peak at 505 nm after annealing for 6 h.Compared the calculated data of these intrinsic defects with the theory of FP-LMTO,we attribute the green(505 nm),orange-red(630 nm) and red(720 nm) emission to the transition from oxygen vacancies to the valence band,the blue emission peak at 440 nm to the transition from zinc interserts to the valence band.The enhancement of exciton excitation peak at 380 nm after annealing indicates that the energy transfer from the exciton to the defaultemission center occurred.