【摘要】 PbTe/CdTe量子阱是一类新型异系低维结构材料,实验观察到具有强的室温中红外光致发光现象。建立了理论模型,计算了PbTe/CdTe量子阱的自发辐射率和光学增益。模型中量子阱分立能级的计算采用k.p包络波函数方法和有限深势阱近似,考虑了PbTe能带结构的各项异性和阱层中应变对能级的影响。计算了PbTe/CdTe量子阱自发辐射谱与带间弛豫和注入载流子浓度间的依赖关系,计算结果与实验观察到的光致发光峰相符合。自发辐射谱线峰位随着注入载流子浓度的增加而出现蓝移,当载流子浓度从2×1017cm-3增加到2.8×1018cm-3,基态发射峰从372 meV蓝移到397 meV,而第一激发态发射峰蓝移量为15 meV。上述蓝移现象是由载流子与载流子及载流子与声子间的相互作用引起的。与PbTe体材料相比,PbTe/CdTe量子阱结构具有更高的增益强度(提高近15倍)和更宽的增益区,因而该体系可能是实现室温连续工作的中红外激光器的理想材料。更多还原

【Abstract】 Intense room-temperature midinfrared luminescent emission has been observed in PbTe/CdTe quantum wells.A theoretical model is developed to study the spontaneous emission and optical gain of the new hetero-structure.In the model the discrete energy level is calculated based on the k·p envelope function method and finite-confinement-potential approximation.Strain effects and anisotropic band structure characteristics of PbTe are taken into account.The dependences of spontaneous emission spectra on intraband relaxation and carrier density are investigated.It is shown that the calculation results are in agreement with the experimental data of photoluminescence.For PbTe/CdTe quantum wells(QWs) with well width of 20 nm,two emission peaks are dominant in the spontaneous emission spectra,which blueshift with carrier density increasing while intraband relaxation is considered in calculation.The shift of ground state emission is from 372 meV to 397 meV and that of the first excited state emission is 15 meV,as the carrier density increases from 2×1017 cm-3 to 2.8×1018 cm-3.The shifts of transition energies are attributed to carrier-carrier and carrier-phonon scattering mechanisms.As compared to the PbTe bulk material,the PbTe/CdTe QWs have higher and broader optical gain,which make them a promising material for mid-infrared laser operating in continuous-wave mode at room temperature.更多还原