Exciton dynamics study of InAs/GaAs quantum dot heterostructures

The elementary excitation dynamics differ qualitatively from those in higherdimensional systems, since the density of states in the zero-dimensional quantum dot (QD) systems is a series of d-functions. Many unique phenomena, including electronic, optical, magnetic, and thermal characteristics, have been observed. As far as the optical properties of the semiconductor QDs are concerned, the excitonic process has attracted a lot of investigations because it is expected to realize very high-efficiency photonic devices due to the Bosonic character of excitons. A key issue is to attain a profound understanding of the corresponding dynamics to facilitate the research for innovative heterodevice architectures. In this work, a steady-state thermal model taking into account the dot size distribution, the random population of density of states, and all of the important mechanisms of exciton dynamics, including radiative and nonradiative recombination, thermal escaping and relaxing, and state filling effects is proposed. These mathematical analyses successfully explain the abnormality of the exciton-related emissions observed in the low dimensional nanostructures. Not only the temperature-and excitation-dependent luminescence measurement systems, but also the metal-organic chemical vapor epitaxy is systematically discussed.