Title 



Strain and band edges in single and coupled cylindrical InAs/GaAs and InP/InGaP selfassembled quantum dots
 
Author 



 
Abstract 



A comparative study is made of the strain distribution in cylindrical InAs/GaAs and InP/InGaP selfassembled quantum dots as obtained from isotropic elasticity theory, the anisotropic continuum mechanical model, and from atomistic calculations. For the isotropic case, the recently proposed approach [J. H. Davies, J. Appl. Phys. 84, 1358 (1998)] is used, while the finiteelement method, the valence force field method, and StillingerWeber potentials are employed to calculate the strain in anisotropic structures. We found that all four methods result in strain distributions of similar shapes, but with notable quantitative differences inside the dot and near the diskmatrix boundary. The variations of the diagonal strains with the height of the quantum dot, with fixed radius, as calculated from all models, are almost linear. Furthermore, the energies of the band edges in the two types of quantum dots are extracted from the multiband effectivemass theory by inserting the strain distributions as obtained by the four models. We demonstrated that all strain models produce effective potentials for the heavy and light holes which agree very well inside the dot. A negligible anisotropy of all normal strains in the (x,y) plane is found, which, providing the axial symmetry of the kinetic part of the multiband effectivemass Hamiltonian, justifies the use of the axial approximation. Strain propagation along the vertical direction is also considered with the aim to study the influence of strain on the electron coupling in stacks of quantum dots. We found that the interaction between the strain fields of the individual quantum dots makes the effective quantum wells for the electrons in the conduction band shallower, thereby counteracting the quantum mechanical coupling. (C) 2002 American Institute of Physics.   
Language 



English
 
Source (journal) 



Journal of applied physics / American Institute of Physics.  New York, N.Y., 1937, currens  
Publication 



New York, N.Y. : American Institute of Physics, 2002
 
ISSN 



00218979 [print]
10897550 [online]
 
Volume/pages 



92:10(2002), p. 58195829
 
ISI 



000178987200036
 
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