Projects per year
Abstract
This thesis describes modeling of carrier relaxation processes in selfassembled quantumdotstructures, with particular emphasis on carrier capture processes in quantum dots. Relaxation by emission of lontitudinal optical (LO) phonons is very efficient in bulk semiconductors and nanostructures of higher dimensionality. Here, we investigate carrier capture processes into quantum dots, mediated by emission of one and two LO phonons. In these investigations is is assumed that the dot is empty initially. In the Case of singlephonon capture we also investigate the influence of the presence of a charge in the quantumdot state to which the capture takes place. In general, capture rates are of the same order as capture rates into an empty dot state, but in some cases the dotsize interval for which the capture process is energetically allowed, is considerably reduced.The above calculations are performed by assuming that the incident carrier is a free carrier described by a plane wave. Therefore, the influence of waves are scattered by the quantum dot have been neglected. At certain wavelengths and dot sizes, the quantum dot can act as a FabryPerot mirror in which the incident carrier travels back and forth in the dot leading to a quasibound state of finite linewidth that resembles the bound states. We investigate the coupling of carriers in quasibound states with LO phonons and demonstrate that they can couple strongly with phonons. This leads to the formation of a mixed carrierphonon mode that is called a polaron.Capture processes mediated by carriercarrier scattering (Auger processes) are investigated and their dependence on quantumdot geometry is studied in detail.
Original language  English 

Place of Publication  Kgs. Lyngby, Denmark 

Publisher  Technical University of Denmark 
Number of pages  159 
ISBN (Print)  8790974395 
Publication status  Published  Apr 2003 
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Projects
 1 Finished

Gain dynamics in quantum dot structures
Magnúsdóttir, I., Mork, J., Bischoff, S., Hvam, J. M., Bjarklev, A. O., Willatzen, M. & Vinter, B.
01/09/1999 → 28/05/2003
Project: PhD