【摘要】 测定了亚单层InGaAs/GaAs量子点-量子阱异质结构在5K下的时间分辨光致发光谱.亚单层量子点的辐射寿命在500ps至800ps之间,随量子点尺寸的增大而增大,与量子点中激子的较小的横向限制能以及激子从小量子点向大量子点的隧穿转移有关.光致发光上升时间强烈依赖于激发强度密度.在弱激发强度密度下,上升时间为35ps,纵光学声子发射为主要的载流子俘获机理.在强激发强度密度下,上升时间随激发强度密度的增加而减小,俄歇过程为主要的载流子俘获机理.该结果对理解亚单层量子点器件的工作特性非常有用.更多还原

【Abstract】 Time-resolved photoluminescence (PL) of sub-monolayer (SML) InGaAs/GaAs quantum-dot-quantum-well heterostructures was measured at 5 K for the first time. The radiative lifetime of SML quantum dots (QDs) increases from 500 ps to 800 ps with the increase of the size of QDs, which is related to the small confinement energy of the excitons inside SML QDs and the exciton transfer from smaller QDs to larger ones through tunneling. The rise time of quantum-dot state PL signal strongly depends on the excitation power density. At low excitation power density, the rise time is about 35 ps, the mechanism of carrier capture is dominated by the emission of longitudinal-optical phonons. At high excitation power density, the rise time decreases as the excitation density increases, and Auger process plays an important role in the carrier capture. These results are very useful for understanding the working properties of sub-monolayer quantum-dot devices.更多还原