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Shallow-donor states in spherical quantum dots with parabolic confinement

Published online by Cambridge University Press:  21 March 2011

C. A. Duque ,
N. Porras-Montenegro ,
M. de Dios-Leyva  and
L. E. Oliveira
C. A. Duque
Affiliation:
Instituto de Física, Universidad de Antioquia, AA 1226, Medellín, Colombia
N. Porras-Montenegro
Affiliation:
Departamento de Física, Universidad del Valle, AA 25360, Cali, Colombia
M. de Dios-Leyva
Affiliation:
Dept. of Theoretical Physics, Univ. of Havana, San Lazaro y L, Vedado, 10400, Havana, Cuba
L. E. Oliveira
Affiliation:
Instituto de Física, Unicamp, CP 6165, Campinas, São Paulo, 13083-970, Brazil
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Abstract

The evidence of a parabolic potential well in quantum wires and dots was reported in the literature, and a parabolic potential is often considered to be a good representation of the “barrier” potential in semiconductor quantum dots. In the present work, the variational and fractionaldimensional space approaches are used in a thorough study of the binding energy of on-center shallow donors in spherical GaAs-Ga1-xAlxAs quantum dots with potential barriers taken either as rectangular [Vb (eV) ??1.247 x for r >] or parabolic [Vb (r) ??β2?r2] isotropic barriers. We define the parabolic potential with a β?parameter chosen so that it results in the same E0 groundstate energy as for the spherical quantum dot of radius R and rectangular potential in the absence of the impurity. Calculations using either the variational or fractional-dimensional approaches both for rectangular and parabolic potential result in essentially the same on-center binding energies provided the dot radius is not too small. This indicates that both potentials are alike representations of the quantum-dot barrier potential for a radius R quantum dot provided the parabolic potential is defined with?β?chosen as mentioned above.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 692: Symposium H – Progress in Semiconductor Materials for Optoelectronic Applications , 2001 , H9.20.1
Copyright
Copyright © Materials Research Society 2002

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