氧化锌量子点浅施主能级增强绿色光致发光光谱的实验证明

利用溶胶-凝胶法制备了粒径在5 nm左右的氧化锌量子点，通过测量氧化锌量子点光致发光光谱、吸收光谱以及荧光寿命得到氧化锌量子点绿光光谱可分为两种且对应不同发光机理。较高能量的绿光光谱是电子由导带底跃迁至氧空穴辐射产生的，而较低能量的则归因于电子由浅施主能级跃迁到氧空位，这种浅施主能级能够增强绿光发射且激发光能量稍小于带隙时绿光光谱相对强度达到最大。其次，实验得到氧化锌量子点的蓝光光谱是由于激发电子从锌间隙能级跃迁至价带产生。该研究提出并分析了氧化锌量子点绿光光谱的两种发光机制，可为其在光学方面的应用提供参考。

Direct Evidences of Shallow Donor Level Enhanced Green Emission in ZnO Quantum Dots

ZnO Quantum dots with particle sizes about 5 nm were prepared by sol-gel method,the research about the photo luminescence(PL)/photoluminescence excitation(PLE)spectrum and the fluorescence lifetime indicated that the green emissions can b e divided into two parts which were attributed to different transit mechanisms.The higher energy green emission was due to the electrons transit from conductio n band to oxygen vacancies while the lower energy green emission was assigned to the electrons transit from the shallow donor levels which enhanced the green em ission to the oxygen vacancies and the shallow donor levels was also the reason why the green emission reach strongest intensity when the excitation energy was a little lower than the band gap energy.While the blue emission can be explaine d by the electrons transiting from Zinc intervals to the valence band.The two m echanisms of green emission are first highlighted and should be considered in th e optical application.