0D Band Gap Engineering by MBE Quantum Rings: Fabrication and Optical Properties

  • Jorge M. GarcíaEmail author
  • Benito Alén
  • Juan Pedro Silveira
  • Daniel Granados
Part of the NanoScience and Technology book series (NANO)


In this chapter we show how it is possible to modify the shape and size of InAs on GaAs self assembled quantum dots grown by Molecular Beam Epitaxy (MBE) by introducing a pause during the capping process, also known as partial overgrowth technique (García et al. in Appl. Phys. Lett. 71:2014, 1997; Appl. Phys. Lett. 72:3172, 1998; Granados and García in Appl. Phys. Lett. 82:2401, 2003). Under certain growth-pause capping conditions it is possible to obtain self-assembled quantum rings. The changes in shape and size lead to a modification of the quantum confinement potential and enables the control over fundamental physical properties, such as the optical emission energy from ground or excited states, the magnitude of its fine structure splitting or the sign of its permanent electric dipole moment.

The partial capping technique has played a key role in the engineering of 0D nanostructures with tailor made properties (Michler et al. in Science 290(5500):2282, 2000; Kiravittaya et al. in Rep. Prog. Phys. 72(4):046502, 2009). For example, it has allowed to fabricate a single-photon source that is based on a single self assembled quantum nanostructure embedded in a high-quality factor microcavity structure (Michler et al. in Science 290(5500):2282, 2000). Another example is the possibility to engineer what has been called “the smallest rings of electricity” (see Chap.  2), which unveil novel magnetic properties associated to non-trivial topologies at the nanoscale (Fomin (ed.) in J. Nanoelectron. Optoelectron., vol. 6. American Scientific, 2011) (see Chaps.  2,  4,  14,  17, and  18).

Typically, the formation of uniform and high quality self-assembled quantum dots, requires fixed growing parameters that does not allow to control independently the size, shape and overall density of the ensemble. The partial capping technique allows to have two separate sets of growing parameters, or “control knobs”: one for optimum QD nucleation and another employed for tuning size and shape during partial capping.

It is well known that the accumulated stress during growth of heteroepitaxial materials systems can lead to the self-assembly of quantum dots. But these driving forces are the very same ones responsible for a disassembling process that takes places during the capping process. Embedding an ensemble of elastically relaxed islands into a matrix material with a smaller lattice parameter, puts into play forces that compete dynamically with the capping process. Some examples of these processes are: atomic segregation, material interchange, surface reconstructions changes, stress-induced melting and de-wetting. The islands on the surface (either pyramid-, dome- or lens-shaped), will not preserve intact their structure after being capped. That is why it is so crucial to understand and control in detail the growth and embedding mechanisms of stressed materials. A way to achieve atomic level control of these dissociation mechanisms is to introduce a growth pause during capping to let the system relax.

This chapter focuses on the understanding and control of the capping process of quantum dots, and how under certain capping conditions, it is possible to obtain quantum rings and other nanostructures with quantum properties engineered at will.

We show in situ, real time, accumulated stress and Reflection High Energy Electron Diffraction (RHEED) measurements during InAs on GaAs(001) growth that shed light on the complicated processes that take place during growth and capping of lattice mismatched, and therefore strained, nanostructures. The experiments show that a large amount of indium melts due to the stress accumulation. This highly mobile material plays a key role on the transformations of self assembled nanostructures. For example, this liquid indium strongly segregates during the capping with GaAs, resulting in asymmetrical final soft barrier potentials.

We present a model to explain the formation of quantum rings under certain partial capping conditions which takes into account the competition processes between de-wetting [see Chap.  2], stress-induced melting of InAs and In/Ga exchange/alloying. We present Atomic Force Microscope (AFM) results of nanostructures with different shapes obtained under various partial capping conditions. The role of As2 in the final formation of rings is also discussed.

Changes in the size and shape of the self-assembled nanostructures induced during the partial capping process allows additional 0D band gap engineering that will change accordingly their optical properties. This is based on measurements of continuous wave photoluminescence (PL), time-resolved PL (TRPL) and photoluminescence excitation (PLE) obtained both, in QRs ensembles, and in single quantum rings. Nanostructures capped under different conditions and with different emission energies are compared. As the diameter to height ratio increases, the radiative lifetime and the splitting between ground and excited states decreases leading to sizeable effects in the recombination dynamics as a function of the temperature. We show that a smaller height and a strong In/Ga exchange induced by the partial capping process are responsible of the reduction of the electrical polarizability and the inversion of the permanent dipole moment in these QRs. Finally, the voltage dependent micro-PL and micro-PLE spectra of charge tunable QRs are presented and analyzed in the framework of a central parabolic confinement model including coulomb interactions in the strong confinement regime.


Molecular Beam Epitaxy Reflection High Energy Electron Diffraction Quantum Ring Permanent Dipole Moment Fundamental Physical Property 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work would not be possible without the support from Spanish projects EPIC-NANOTICS (MINECO TEC2011-29120-C05-04), Q&C Light (CAM S2009ESP-1503), NANOSELF project (TIC2002-04096), Comunidad Autónoma de Madrid (07T/0062/2000), and CICYT (TIC99-1035-C02); and EU project NANOMAT (G5RD-CT-2001-00545).


  1. 1.
    J.M. García, G. Medeiros-Ribeiro, K. Schmidt, T. Ngo, J.L. Feng, A. Lorke, J. Kotthaus, P. Petroff, Appl. Phys. Lett. 71, 2014 (1997) ADSCrossRefGoogle Scholar
  2. 2.
    J.M. García, T. Mankad, P.O. Holtz, J. Wellman, P.M. Petroff, Appl. Phys. Lett. 72, 3172 (1998) ADSCrossRefGoogle Scholar
  3. 3.
    D. Granados, J.M. García, Appl. Phys. Lett. 82, 2401 (2003) ADSCrossRefGoogle Scholar
  4. 4.
    P. Michler, A. Kiraz, C. Becher, W.V. Schoenfeld, P.M. Petroff, L. Zhang, E. Hu, A. Imamoglu, Science 290(5500), 2282 (2000) ADSCrossRefGoogle Scholar
  5. 5.
    S. Kiravittaya, A. Rastelli, O.G. Schmidt, Rep. Prog. Phys. 72(4), 046502 (2009) ADSCrossRefGoogle Scholar
  6. 6.
    V.M. Fomin (ed.), A special issue on Modern Advancements in Experimental and Theoretical Physics of Quantum Rings. J. Nanoelectron. Optoelectron. 6 (American Scientific, 2011) Google Scholar
  7. 7.
    D.J. Eaglesham, M. Cerullo, Phys. Rev. Lett. 64, 1943 (1990) ADSCrossRefGoogle Scholar
  8. 8.
    D. Leonard, M. Krishnamurthy, C.M. Reaves, S. Denbaars, P. Petroff, Appl. Phys. Lett. 63, 3203 (1993) ADSCrossRefGoogle Scholar
  9. 9.
    J.Y. Marzin, J. Gerald, A. Izrael, D. Barrier, G. Gastard, Phys. Rev. Lett. 713, 716 (1994) ADSCrossRefGoogle Scholar
  10. 10.
    R.J. Warburton, C. Schäflein, D. Haft, F. Bickel, A. Lorke, K. Karrai, J.M. García, W. Schoenfeld, P.M. Petroff, Nature 405, 926 (2000) ADSCrossRefGoogle Scholar
  11. 11.
    A. Lorke, R.J. Luyken, A.O. Govorov, J.P. Kotthaus, J.M. García, P.M. Petroff, Phys. Rev. Lett. 84, 2223 (2000) ADSCrossRefGoogle Scholar
  12. 12.
    R.J. Warburton, C. Schulhauser, D. Haft, C. Schäflein, K. Karrai, J.M. García, W. Schoenfeld, P.M. Petroff, Phys. Rev. B 65, 113303 (2002) ADSCrossRefGoogle Scholar
  13. 13.
    B. Alén, J. Martínez-Pastor, D. Granados, J.M. García, Phys. Rev. B 72, 155331 (2005) ADSCrossRefGoogle Scholar
  14. 14.
    N.A.J.M. Kleemans, I.M.A. Bominaar-Silkens, V.M. Fomin, V.N. Gladilin, D. Granados, A.G. Taboada, J.M. García, P. Offermans, U. Zeitler, P.C.M. Christianen, J.C. Maan, J.T. Devreese, P.M. Koenraad, Phys. Rev. Lett. 99, 146808 (2007) ADSCrossRefGoogle Scholar
  15. 15.
    Y. Aharonov, D. Bohm, Phys. Rev. B 115, 485 (1959) ADSCrossRefzbMATHMathSciNetGoogle Scholar
  16. 16.
    P.B. Joyce, T.J. Krzyzewski, G.R. Bell, T.S. Jones, S. Malik, D. Childs, R. Murray, Phys. Rev. B 62, 10891 (2000) ADSCrossRefGoogle Scholar
  17. 17.
    T. Kawai, H. Yonezu, Y. Ogasawara, D. Saito, K. Pak, J. Cryst. Growth 201, 1146 (1999) ADSGoogle Scholar
  18. 18.
    J. Moison, C. Guille, F. Houzay, F. Barthe, M.V. Rompay, Phys. Rev. B 40, 6149 (1989) ADSCrossRefGoogle Scholar
  19. 19.
    J. Silveira, F. Briones, J. Cryst. Growth 201–202, 113 (1999) CrossRefGoogle Scholar
  20. 20.
    J.M. García, J. Silveira, F. Briones, Appl. Phys. Lett. 77, 409 (2000) ADSCrossRefGoogle Scholar
  21. 21.
    R. Blossey, A. Lorke, Phys. Rev. E 65, 021603 (2002) ADSCrossRefGoogle Scholar
  22. 22.
    M. Grundmann, O. Stier, D. Bimberg, Phys. Rev. B 52, 11969 (1995) ADSCrossRefGoogle Scholar
  23. 23.
    J.P. Silveira, J.M. García, F. Briones, J. Cryst. Growth 227/228, 995 (2001) ADSCrossRefGoogle Scholar
  24. 24.
    O.B.E. Tournier, K. Ploog, Appl. Phys. Lett. 60, 287 (1992) Google Scholar
  25. 25.
    J.M. García, L. González, M.U. González, J.P. Silveira, Y. González, F. Briones, J. Cryst. Growth 227–228, 975 (2001) CrossRefGoogle Scholar
  26. 26.
    D. Alonso-Álvarez, J.M. Ripalda, B. Alén, J.M. Llorens, A. Rivera, F. Briones, Adv. Mater. 23, 5256 (2011) CrossRefGoogle Scholar
  27. 27.
    J. Floro, E. Chason, S. Lee, R. Twesten, R. Hwang, L. Freund, J. Electron. Mater. 26, 969 (1997) ADSCrossRefGoogle Scholar
  28. 28.
    M.U. González, L. González, J.M. García, Y. González, J.P. Silveira, F. Briones, Microelectron. J. 35(1), 13 (2004) CrossRefGoogle Scholar
  29. 29.
    J. Massies, F. Turco, A. Saletes, J. Contour, J. Cryst. Growth 80, 307 (1987) ADSCrossRefGoogle Scholar
  30. 30.
    D.J. Bottomley, Appl. Phys. Lett. 80, 4747 (2002) ADSCrossRefGoogle Scholar
  31. 31.
    T. Mano, T. Kuroda, S. Sanguinetti, T. Ochiai, T. Tateno, J. Kim, T. Noda, M. Kawabe, K. Sakoda, G. Kido, N. Koguchi, Nano Lett. 5, 425 (2005) ADSCrossRefGoogle Scholar
  32. 32.
    Q. Xie, P. Chen, A. Madhukar, Appl. Phys. Lett. 65, 2051 (1994) ADSCrossRefGoogle Scholar
  33. 33.
    A. Lorke, R. Blossey, J.M. García, M. Bichler, G. Abstreiter, Mater. Sci. Eng. B 88, 225 (2002) CrossRefGoogle Scholar
  34. 34.
    P.B. Joyce, T.J. Krzyzewski, G.R. Bell, B.A. Joyce, T.S. Jones, Phys. Rev. B 58, R15981 (1998) ADSCrossRefGoogle Scholar
  35. 35.
    Y. Horikoshi, H. Yamaguchi, F. Briones, M. Kawashima, J. Cryst. Growth 105, 326 (1990) ADSCrossRefGoogle Scholar
  36. 36.
    T. Ogura, D. Kishimoto, T. Nishinaga, J. Cryst. Growth 226, 179 (2001) ADSCrossRefGoogle Scholar
  37. 37.
    D. Granados, J.M. García, T. Ben, S.I. Molina, Appl. Phys. Lett. 86, 071918 (2005) ADSCrossRefGoogle Scholar
  38. 38.
    P. Offermans, P.M. Koenraad, J.H. Wolter, D. Granados, J.M. García, V.M. Fomin, V.N. Gladilin, J.T. Devreese, Appl. Phys. Lett. 87, 131902 (2005) ADSCrossRefGoogle Scholar
  39. 39.
    R.A. Römer, R.E. Raikh, Phys. Rev. B 62, 7045 (2000) ADSCrossRefGoogle Scholar
  40. 40.
    J. Song, S.E. Ulloa, Phys. Rev. B 63, 125302 (2001) ADSCrossRefGoogle Scholar
  41. 41.
    H. Hu, J.L. Zhu, D.J. Li, J.J. Xiong, Phys. Rev. B 63, 195307 (2001) ADSCrossRefGoogle Scholar
  42. 42.
    I. Galbraith, F.J. Braid, R.J. Warburton, Phys. Status Solidi A 190, 781 (2002) ADSCrossRefGoogle Scholar
  43. 43.
    A.O. Govorov, S.E. Ulloa, K. Karrai, R.J. Warburton, Phys. Rev. B 66, 081309 (2002) ADSCrossRefGoogle Scholar
  44. 44.
    M. Bayer, M. Korkusinski, P. Hawrylak, T. Gutbrod, M. Michel, A. Forchel, Phys. Rev. Lett. 90, 186801 (2003) ADSCrossRefGoogle Scholar
  45. 45.
    E. Ribeiro, A.O. Govorov, J.G.M.R.W. Carvalho, Phys. Rev. Lett. 92, 126402 (2004) ADSCrossRefGoogle Scholar
  46. 46.
    I.R. Sellers, V.R. Whiteside, L. Kuskovsky, A.O. Govorov, B.D. McCombe, Phys. Rev. Lett. 100, 136405 (2008) ADSCrossRefGoogle Scholar
  47. 47.
    A.M. Fischer, J.V.L. Campo, M.E. Portnoi, R.A. Römer, Phys. Rev. Lett. 102, 096405 (2009) ADSCrossRefGoogle Scholar
  48. 48.
    M.D. Teodoro, J.V.L.R.V.L. Campo, J.G.E.M.E. Marega, Y.G. Gobato, F. Iikawa, M.J.S.P. Brasil, Z.Y. AbuWaar, V.G. Dorogan, Y.I. Mazur, M. Benamara, G.J. Salamo, Phys. Rev. Lett. 104, 086401 (2010) ADSCrossRefGoogle Scholar
  49. 49.
    F. Ding, N. Akopian, B. Li, U. Perinetti, A. Govorov, F.M. Peeters, C.C.B. Bufon, C. Deneke, Y.H. Chen, A. Rastelli, O.G. Schmidt, V. Zwiller, Phys. Rev. B 82, 075309 (2010) ADSCrossRefGoogle Scholar
  50. 50.
    J.M. Llorens, C. Trallero-Giner, A. García-Cristobal, A. Cantarero, Phys. Rev. B 64, 035309 (2001) ADSCrossRefGoogle Scholar
  51. 51.
    O. Voskoboynikov, Y. Li, H.M. Lu, C.F. Shih, C.P. Lee, Phys. Rev. B 66, 155306 (2002) ADSCrossRefGoogle Scholar
  52. 52.
    J.A. Barker, R.J. Warburton, E.P. O’Reilly, Phys. Rev. B 69, 035327 (2004) ADSCrossRefGoogle Scholar
  53. 53.
    J.I. Climente, J. Planelles, F. Rajadell, J. Phys. Condens. Matter 17, 1573 (2005) ADSCrossRefGoogle Scholar
  54. 54.
    J.I. Climente, J. Planelles, W. Jaskólski, Phys. Rev. B 68, 075307 (2003) ADSCrossRefGoogle Scholar
  55. 55.
    A. Emperador, M. Pi, M. Barranco, A. Lorke, Phys. Rev. B 62, 4573 (2000) ADSCrossRefGoogle Scholar
  56. 56.
    A. Puente, L. Serra, Phys. Rev. B 63, 125334 (2001) ADSCrossRefGoogle Scholar
  57. 57.
    H. Hu, G.M. Zhang, J.L. Zhu, J.J. Xiong, Phys. Rev. B 63, 045320 (2001) ADSCrossRefGoogle Scholar
  58. 58.
    J. Gomis, J. Martínez-Pastor, B. Alén, D. Granados, J. García, P. Roussignol, Eur. Phys. J. B 54, 471 (2006) ADSCrossRefGoogle Scholar
  59. 59.
    B. Alén, J. Bosch, J. Martínez-Pastor, D. Granados, J.M. García, L. González, Phys. Rev. B 75, 045319 (2007) ADSCrossRefGoogle Scholar
  60. 60.
    R.J. Warburton, B.T. Miller, C.S. Dürr, C. Bödefeld, K. Karrai, J.P. Kotthaus, G. Medeiros-Ribeiro, P.M. Petroff, S. Huant, Phys. Rev. B 58, 16221 (1998) ADSCrossRefGoogle Scholar
  61. 61.
    R. Heitz, A. Kalburge, Q. Xie, M. Grundmann, P. Chen, A. Hoffmann, A. Madhukar, D. Bimberg, Phys. Rev. B 57, 9050 (1998) ADSCrossRefGoogle Scholar
  62. 62.
    J.A. Barker, E.P. O’Reilly, Phys. Rev. B 61, 13840 (2000) ADSCrossRefGoogle Scholar
  63. 63.
    A. Greilich, M. Schwab, T. Berstermann, T. Auer, R. Oulton, D. Yakovlev, M. Bayer, V. Stavarache, D. Reuter, A. Wieck, Phys. Rev. B 73, 045323 (2006) ADSCrossRefGoogle Scholar
  64. 64.
    E.E. Mendez, G. Bastard, L.L. Chang, L. Esaki, H. Morkoc, R. Fischer, Phys. Rev. B 26, 7101 (1982) ADSCrossRefGoogle Scholar
  65. 65.
    O. Stier, M. Grundmann, D. Bimberg, Phys. Rev. B 59, 5688 (1999) ADSCrossRefGoogle Scholar
  66. 66.
    W. Sheng, J.P. Leburton, Phys. Rev. B 67, 125308 (2003) ADSCrossRefGoogle Scholar
  67. 67.
    H. Pettersson, R. Warburton, A. Lorke, K. Karrai, J. Kotthaus, J. García, P. Petroff, Physica E 6, 510 (2000) ADSCrossRefGoogle Scholar
  68. 68.
    R. Oulton, J.J. Finley, A.I. Tartakovskii, D.J. Mowbray, M.S. Skolnick, M. Hopkinson, A. Vasanelli, R. Ferreira, G. Bastard, Phys. Rev. B 68, 235301 (2003) ADSCrossRefGoogle Scholar
  69. 69.
    J.J. Finley, P.W. Fry, A.D. Ashmore, A. Lemaitre, A.I. Tartakovskii, R. Oulton, D.J. Mowbray, M.S. Skolnick, M. Hopkinson, P.D. Buckle, P.A. Maksym, Phys. Rev. B 63, R161305 (2001) ADSCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Jorge M. García
    • 1
    Email author
  • Benito Alén
    • 1
  • Juan Pedro Silveira
    • 1
  • Daniel Granados
    • 1
    • 2
  1. 1.Instituto de Microelectrónica de MadridTres CantosSpain
  2. 2.IMDEA NanocienciaMadridSpain

Personalised recommendations