低浓度掺杂的量子点粒度分布对荧光辐射谱的影响

Effect of Size Distribution of Quantum Dots with Low Doping Concentration on Photoluminescence Emission Spectrum

当量子点粒度分布为高斯分布时,应用有效质量近似,在低浓度掺杂范围内,得到了量子点荧光辐射谱线形函数与量子点尺寸之间的一般关系,解释了尺寸涨落对线形展宽的影响。对II-VI族的Cd Se量子点和IV-VI族的Pb Se量子点的数值计算表明:量子点荧光谱线的半峰全宽、荧光辐射强度、峰值波长等与实验结果基本一致。量子点尺寸的粒度分布对荧光辐射谱线展宽有较大的影响。荧光辐射谱展宽是一种非均匀展宽。

A general expression of the photoluminescence （PL）-spectral shape depending on the size distribution of quantum dots （QDs） in the condition of low doping concentration is presented, using the effective mass approximation and supposing a Gaussian distribution of QD sizes. Effect of the size fluctuation on the PL-broadened line is discussed. As an example, the PL-broadened lines of both IV-VI CdSe QDs and II-VI PbSe QDs are calculated. There is evidence to show that the calculated PL intensity, PL-peak wavelength and full width at half maximum of the PL-broadened line are in consistent with the experimental measurements. The size distribution of QDs has primary effect on the PL-broadened line. The PL-broadened line is an inhomogeneous broadening.