PbTe/CdTe量子点的光学增益

Optical gain in PbTe/CdTe quantum dots

PbTe/CdTe量子点是一类新型异系低维结构材料,实验发现具有强的室温中红外光致发光现象.为研究这一材料体系的发光特性,建立了理论模型,计算了PbTe/CdTe量子点的光学跃迁和增益.模型基于k.p包络波函数方法并考虑了PbTe能带结构的各向异性.分析了量子点光学增益与量子点尺寸、注入载流子浓度的关系.结果表明,当注入载流子浓度在(0.3—3)×1018cm-3范围时,尺寸为15—20nm的量子点可以产生大于5000cm-1的光学增益,增益峰位于400meV(3.1μm)附近.量子点尺寸的增大使得增益峰强减小,而量子点尺寸的减小又导致产生光学增益需要更高的注入载流子浓度,优化的PbTe量子点尺寸为15—20nm.

A theoretical model is developed to study the optical transition and optical gain of PbTe/CdTe quantum dots. The model is based on the k ·p envelope function approach, and anisotropic band structure characteristics of PbTe are taken into consideration. The relationships of optical gain of PbTe/CdTe quantum dots vs dot size and injection carrier density are given. The theoretical results suggest that PbTe/CdTe quantum dots with dot size of 15-20 nm are promising materials for mid-infrared lasers, which may produce optical gain higher than 5000 cm^-1 when the injection carrier density ranges （0.3-3） × 10^18 cm^-3 . The optical gain decreases with dot size increasing. However, higher injection carrier density is required for PbTe/CdTe quantum