Title 



Exciton states and oscillator strength in two vertically coupled InP/InGaP quantum discs
 
Author 



 
Abstract 



Quantum mechanical coupling and strain in two vertically arranged InP/InGaP quantum dots is studied as a function of the size of the dots and the spacer thickness. The strain distribution is determined by the continuum mechanical model, while the singleband effectivemass equation and the multiband k (.) p theory are employed to compute the conduction and valence band energy levels, respectively. The exciton states are obtained from an exact diagonalization approach, and we also compute the oscillator strength for recombination. We found that the light holes are confined by strain to the spacer, which is the reason that the hole states exhibit coupling at much larger distances as compared with the electrons. At small d, the doublet structure of the hole energy levels arises as a consequence of the relocation of the light hole from the matrix to the regions locatedoutside the stack, close to the dotmatrix interface. When d varies, the exciton ground state exhibits numerous anticrossings with other states, which are related to the changing spatial localization of the hole as a function of d. The oscillator strength of the exciton recombination is strongly reduced in a certain range of spacer thicknesses, which effectively turns a bright exciton state into a dark one. This effect is associated with anticrossings between exciton energy levels.   
Language 



English
 
Source (journal) 



Journal of physics : condensed matter.  London  
Publication 



London : 2004
 
ISSN 



09538984
 
Volume/pages 



16:47(2004), p. 86338652
 
ISI 



000225796800016
 
Full text (Publishers DOI) 


  
Full text (publishers version  intranet only) 


  
