Effect of wetting layers on the strain and electronic structure of InAs self-assembled quantum dots

The effect of wetting layers on the strain and electronic structure of InAs self-assembled quantum dots grown on GaAs is investigated with an atomistic valence-force-field model and an empirical tight-binding model. By comparing a dot with and without a wetting layer, we find that the inclusion of the wetting layer weakens the strain inside the dot by only 1% relative change, while it reduces the energy gap between a confined electron and hole level by as much as 10%. The small change in the strain distribution indicates that strain relaxes only little through the thin wetting layer. The large reduction of the energy gap is attributed to the increase of the confining-potential width rather than the change of the potential height. First-order perturbation calculations or, alternatively, the addition of an InAs disk below the quantum dot confirm this conclusion. The effect of the wetting layer on the wave function is qualitatively different for the weakly confined electron state and the strongly confined hole state. The electron wave function shifts from the buffer to the wetting layer, while the hole shifts from the dot to the wetting layer.

[1]  J. Groenen,et al.  Strain distribution and optical phonons in InAs/InP self-assembled quantum dots , 1999 .

[2]  Andrew J. Williamson,et al.  InAs quantum dots: Predicted electronic structure of free-standing versus GaAs-embedded structures , 1999 .

[3]  Gerhard Klimeck,et al.  Strain effects in large-scale atomistic quantum dot simulations , 2003 .

[4]  Richard M. Martin,et al.  Elastic Properties of ZnS Structure Semiconductors , 1970 .

[5]  Anupam Madhukar,et al.  Punctuated island growth: An approach to examination and control of quantum dot density, size, and shape evolution , 1999 .

[6]  Andrew G. Glen,et al.  APPL , 2001 .

[7]  Tight-binding study of the influence of the strain on the electronic properties of InAs 'GaAs quantum dots , 2003, cond-mat/0306129.

[8]  J. M. Rorison,et al.  Quantum Dot Heterostructures , 2000 .

[9]  Harris,et al.  Vertically aligned and electronically coupled growth induced InAs islands in GaAs. , 1996, Physical review letters.

[10]  D. Bimberg,et al.  Electronic and optical properties of strained quantum dots modeled by 8-band k⋅p theory , 1999 .

[11]  M. Bayer,et al.  Excitonic energy shell structure of self-assembled InGaAs/GaAs quantum dots. , 2004, Physical review letters.

[12]  J. Leburton,et al.  Absence of correlation between built-in electric dipole moment and quantum Stark effect in single InAs/GaAs self-assembled quantum dots , 2002, cond-mat/0204579.

[13]  A. Zunger,et al.  Theoretical interpretation of the experimental electronic structure of lens shaped, self-assembled InAs/GaAs quantum dots , 2000, cond-mat/0003055.

[14]  Craig E. Pryor,et al.  Geometry and material parameter dependence of InAs/GaAs quantum dot electronic structure , 1999 .

[15]  T. Boykin,et al.  Diagonal parameter shifts due to nearest-neighbor displacements in empirical tight-binding theory , 2002 .

[16]  M E Flatté,et al.  Accuracy of circular polarization as a measure of spin polarization in quantum dot qubits. , 2003, Physical review letters.

[17]  Richard M. Martin,et al.  Self-consistent calculation of the electronic structure and electron-electron interaction in self-assembled InAs-GaAs quantum dot structures , 1998 .

[18]  M. S. Skolnick,et al.  Inverted electron-hole alignment in InAs-GaAs self-assembled quantum dots. , 2000, Physical review letters.

[19]  J. M. Moison,et al.  Self‐organized growth of regular nanometer‐scale InAs dots on GaAs , 1994 .

[20]  Jean-Pierre Leburton,et al.  Electron-hole alignment in InAs/GaAs self-assembled quantum dots: Effects of chemical composition and dot shape , 2001 .

[21]  Boundary conditions for the electronic structure of finite-extent embedded semiconductor nanostructures , 2003, cond-mat/0311461.

[22]  Jerry R. Meyer,et al.  Band parameters for III–V compound semiconductors and their alloys , 2001 .

[23]  D. Bimberg,et al.  InAs/GaAs pyramidal quantum dots: Strain distribution, optical phonons, and electronic structure. , 1995, Physical review. B, Condensed matter.

[24]  C. Pryor.  Eight-band calculations of strained InAs/GaAs quantum dots compared with one-, four-, and six-band approximations , 1997, cond-mat/9710304.

[25]  M. Henini,et al.  Quantum-dot phonons in self-assembled InAs/GaAs quantum dots: Dependence on the coverage thickness , 2000 .

[26]  P. Harrison,et al.  Presentation and experimental validation of a single-band, constant-potential model for self-assembled InAs/GaAs quantum dots , 2000 .

[27]  A. J. Williamson,et al.  COMPARISON OF TWO METHODS FOR DESCRIBING THE STRAIN PROFILES IN QUANTUM DOTS , 1997, cond-mat/9711126.

[28]  J. Leburton,et al.  Enhanced intraband transitions with strong electric-field asymmetry in stacked InAs/GaAs self-assembled quantum dots , 2001 .

[29]  P. N. Keating,et al.  Effect of Invariance Requirements on the Elastic Strain Energy of Crystals with Application to the Diamond Structure , 1966 .

[30]  Lin-Wang Wang,et al.  Electronic structures of [110]-faceted self-assembled pyramidal InAs/GaAs quantum dots , 1999 .

[31]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[32]  Nobuhiko P. Kobayashi,et al.  In situ, atomic force microscope studies of the evolution of InAs three‐dimensional islands on GaAs(001) , 1996 .

[33]  A. Zunger,et al.  Electronic structure consequences of In/Ga composition variations in self-assembled In x Ga 1-x As/GaAs alloy quantum dots , 2001 .