CdTe和CdTe/CdS量子点的量子尺寸效应

利用水热法合成了三种不同尺寸的单核CdTe量子点和核壳CdTe/CdS量子点。应用Top-hat Z-scan技术在纳秒、皮秒、飞秒激光脉冲作用下研究了三种不同尺寸单核CdTe量子点的非线性吸收特性。实验结果表明:在不同激光脉冲作用下三种不同尺寸的CdTe量子点的非线性吸收特性均表现为饱和吸收，并且均呈现出随着量子点尺寸的减小，其非线性吸收特性增大的趋势。为了进一步研究量子点尺寸的变化对非线性吸收特性的影响，又在飞秒激光脉冲作用下研究了核壳CdTe/CdS量子点的非线性吸收特性；随着包壳时间的增加，壳层厚度增加，量子点尺寸增加，其非线性吸收特性呈减小趋势，并且核壳CdTe/CdS量子点的非线性吸收特性明显优于单核CdTe量子点；分析讨论了单核CdTe量子点与核壳CdTe/CdS量子点的非线性吸收特性和量子尺寸效应机制，实验结果表明合成的量子点样品均具有良好的量子尺寸效应。

Quantum size effect of CdTe and CdTe/CdS quantum dots

Three CdTe quantum dots and CdTe/CdS quantum dots with different sizes were synthesized by hydrothermal method. The nonlinear absorption properties of CdTe quantum dots with three different sizes were investigated by the Top-hat Z-scan technique under ns, ps and fs laser pulses. The experimental results show that the nonlinear absorption properties of CdTe quantum dots with three different sizes are saturated absorption under different laser pulses, and all of them show the increasing tendency of nonlinear absorption characteristics with the decrease of quantum dots size. In order to further study the effect of quantum dots size on the nonlinear absorption properties, the nonlinear absorption properties of CdTe/CdS quantum dots were investigated under fs laser pulse. With the increase of cladding time, the thickness of shell increases, the size of quantum dots increases, and the nonlinear absorption properties decrease. And the nonlinear absorption properties of CdTe/CdS quantum dots were better than those of CdTe quantum dots. The nonlinear absorption properties and the quantum size effect mechanism of CdTe quantum dots and CdTe/CdS quantum dots were discussed, the experimental results show that the synthetic quantum dots have good quantum size effect.