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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.
The time-resolved photoluminescence spectra of sub-monolayer InGaAs / GaAs quantum dot-quantum well heterostructures were measured at 5 K. The radiation lifetime of sub-monolayer quantum dots was between 500 and 800 ps. With the increase of quantum dot size , Which is related to the smaller lateral confinement of excitons in quantum dots and the tunneling transfer of excitons from small quantum dots to large quantum dots.The photoluminescence rise time strongly depends on the excitation intensity density.At the weak excitation intensity density , The rise time is 35ps, and longitudinal optical phonon emission is the main carrier-trapping mechanism.In the case of strong excitation intensity, the rise time decreases with the increase of excitation intensity density, and the Auger process is the main carrier-trapping mechanism This result is useful for understanding the operating characteristics of sub-monolayer quantum dot devices.