铜掺杂对硒化锌量子点光电子特性的影响

Effect of Cu doping on photoelectron characteristics of ZnSe quantum dots

利用水相合成法制备Cu:Zn Se量子点。采用表面光伏技术和紫外-可见吸收光谱,辅以高分辨透射电子显微镜,激光拉曼谱和X射线衍射图谱,研究掺杂铜对于Cu:Zn Se量子点微结构和光生电荷转移跃迁行为的影响。结果表明,掺铜后Cu:Zn Se量子点主带隙电荷转移跃迁产生的SPV响应强度比未掺铜Zn Se量子点高一倍。Cu:Zn Se量子点对应的主带隙表面光伏响应峰发生明显红移,表明铜掺杂态的电子能级位于导带底附近,并具有受体能级特征。研究发现,由于掺杂Cu2+离子导致Zn Se量子点光学带隙变小,而且变小的程度随掺杂量的增加而有所提高。实验证实,由于Cu2+离子的引入,Zn Se量子点立方闪锌矿结构(111)晶面X射线衍射峰出现分叉现象,它们分别对应于立方硒铜矿(101)和(102)晶面。

Cu： ZnSe quantum dots was prepared by the water phase synthesis method. Surface photovoltaic technique and UV-Vis absorption spectroscopy,combined with high-resolution transmission electron microscopy,laser Raman spectroscopy and X-ray diffraction were performed to investigate the effect of Cu doping on the microstructure and photo-generated transition behavior of Cu：ZnSe quantum dots. The results showed that the surface photovoltaic response intensity of the main bandgap charge shift for Cu：ZnSe quantum dots is twice as high as that of the ZnSe quantum dots. And a remarkable red shift was observed in the corresponding photovoltaic response peak of main bandgap surface for Cu： ZnSe quantum dots,indicating that the electronic energy level of doped Cu state was located near the bottom of the conduction band,and possessed the receptor level characteristics. It was found that the optical band gap of ZnSe quantum dots became smaller and the degree of miniaturization increased with the doping amount due to the addition of Cu^2＋ ions. The results also veritified that the X-ray diffraction peak of the（ 111） plane of the ZnSe quantum dot with a cubic sphalerite structure are bifurcated due to the introduction of Cu^2＋ ions,which correspond to the cubic（ 101） and（ 102）planes.