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Highly uniform arrays of epitaxial Ge quantum dots with interdot spacing of 50 nm

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Abstract

Periodic, highly uniform arrays of dome-like Ge quantum dots (QDs) with 50 nm interdot pitch have been achieved on Si (001). The Si surface was patterned using ultra-low-dose focused ion beam and defect-selective etching, resulting in a continuously height-modulated, “egg-carton” morphology. The directed self-assembly process is robust, occurring across a range of ion doses, growth temperatures, and deposition rates. By selectively etching off the Ge dots to reveal the underlying Si surface just prior to Ge growth, we showed that Ge QDs preferentially formed on crowns (regions of negative curvature) rather than pits (regions of positive curvature) as is mostly seen in the literature. The width of the QD size distribution mimics that of the underlying substrate pattern, indicative of a complete lack of coarsening during the Ge growth, despite the small length scales, and extensive mass transport leading to QD formation.

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References

  1. Z. Zhong and G. Bauer: Site-controlled and size-homogeneous Ge islands on prepatterned Si (001) substrates. Appl. Phys. Lett. 84, 1922 (2004).

    Article  CAS  Google Scholar 

  2. D. Grützmacher, T. Fromherz, C. Dais, J. Stangl, E. Müller, Y. Ekinci, H.H. Solak, H. Sigg, R.T. Lechner, E. Wintersberger, S. Birner, V. Holy’, and G. Bauer: Three-dimensional Si/Ge quantum dot crystals. Nano Lett. 7, 3150–3156 (2007).

    Article  Google Scholar 

  3. C.E. Pryor, M.E. Flatté, and J. Levy: Electrical manipulation of an electronic two-state system in Ge quantum dots. Appl. Phys. Lett. 95, 232103 (2009).

    Article  Google Scholar 

  4. T. Fromherz, J. Stangl, R.T. Lechner, E. Wintersberger, G Bauer, V. Holy, C. Dais, E. Müller, H. Sigg, H.H. Solak, and D. Grützmacher: 3D SiGe quantum dot crystals: Structural characterization and electronic coupling. Int. J. Mod. Phys. B 23, 2836–2841 (2009).

    Article  CAS  Google Scholar 

  5. Z. Zhong, A. Halilovic, and M. Mühlberger, F. Schäffler, and G. Bauer: Ge island formation on stripe-patterned Si(001) substrates. Appl. Phys. Lett. 82, 445 (2003).

    Article  CAS  Google Scholar 

  6. F.M. Ross, M. Kammler, M.C. Reuter, and R. Hull: In-situ observations of self-assembled island nucleation on patterned substrates. Philos. Mag. 84, 2687–2702 (2004).

    Article  CAS  Google Scholar 

  7. A. Karmous, A. Cuenat, A. Ronda, I. Berbezier, S. Atha, and R. Hull: Ge dot organization on Si substrates patterned by focused ion beam. Appl. Phys. Lett. 85, 6401 (2004).

    Article  CAS  Google Scholar 

  8. T.I. Kamins and R.S. Williams: Lithographic positioning of self-assembled Ge islands on Si(001). Appl. Phys. Lett. 71, 1201 (1997).

    Article  CAS  Google Scholar 

  9. T. Kitajima, B. Liu, and S.R. Leone: Two-dimensional periodic alignment of self-assembled Ge islands on patterned Si(001) surfaces. Appl. Phys. Lett. 80, 497 (2002).

    Article  CAS  Google Scholar 

  10. G. Jin, J.L. Liu, S.G. Thomas, Y.H. Luo, K.L. Wang, and B-Y. Nguyen: Perfect alignment of self-organized Ge islands on pre-grown Si stripe mesas. Appl. Phys. A: Mater. Sci. Process. 70, 551–554 (2000).

    Article  CAS  Google Scholar 

  11. T.S. Yoon, H-M. Kim, K-B. Kim, D.Y. Ryu, T.P. Russell, Z. Zhao, J. Liu, and Y-H. Xie: Study of growth behaviour and microstructure of epitaxially grown self-assembled Ge quantum dots on nanometer-scale patterned SiO 2/Si(001) substrates. Phys. Status Solidi 246, 721–724 (2009).

    Article  CAS  Google Scholar 

  12. G. Katsaros, P. Spathis, M. Stoffel, F. Fournel, M. Mongillo, V. Bouchiat, F. Lefloch, A. Rastelli, O.G. Schmidt, and S. DeFrancheschi: Hybrid superconductor-semiconductor devices made from self-assembled SiGe nanocrystals on silicon. Nat. Nanotechnol. 5, 458–464 (2010).

    Article  CAS  Google Scholar 

  13. K.L. Wang, D. Cha, J. Liu, and C. Chen: Ge/Si self-assembled quantum dots and their optoelectronic device applications. Proc. IEEE 95, 1866–1883 (2007).

    Article  CAS  Google Scholar 

  14. K. Brunner: Si/Ge nanostructures. Rep. Prog. Phys. 65, 27–72 (2002).

    Article  CAS  Google Scholar 

  15. K. Eberl, O.G. Schmidt, R. Duschl, O. Kienzle, E. Ernst, and Y. Rau: Self-assembling SiGe and SiGeC nanostructures for light emitters and tunneling diodes. Thin Solid Films 369, 33–38 (2000).

    Article  CAS  Google Scholar 

  16. O.G. Schmidt, U. Denker, M. Dashiell, N.Y. Jin-Phillipp, K. Eberl, R. Schreiner, H. Grabeldinger, H. Schweizer, S. Christiansen, and F. Ernst: Laterally aligned Ge/Si islands: A new concept for faster field-effect transistors. Mater. Sci. Eng., B 89, 101–105 (2002).

    Article  Google Scholar 

  17. G. Fiedler and P. Kratzer: Theoretical prediction of improved figure-of-merit in Si/Ge quantum dot superlattices. New J. Phys. 23, 2836–2841 (2013).

    Google Scholar 

  18. D. Srolovitz: On the stability of surfaces of stressed solids. Acta Metall. 37, 621–625 (1989).

    Article  Google Scholar 

  19. G. Medeiros-Ribeiro, A. Bratkovski, T.I. Kamins, D. Ohlberg, and R.S. Williams: Shape transition of germanium nanocrystals on a silicon (001) surface from pyramids to domes. Science 279, 353–356 (1998).

    Article  CAS  Google Scholar 

  20. M. Brehm, F. Montalenti, M. Grydlik, G. Vastola, H. Lichtenberger, N. Hrauda, M.J. Beck, T. Fromherz, F. Schäffler, L. Miglio, and G. Bauer: Key role of the wetting layer in revealing the hidden path of Ge/Si(001) Stranski-Krastanow growth onset. Phys. Rev. B 80, 205321 (2009).

    Article  Google Scholar 

  21. B. Yang, F. Liu, and M. Lagally: Local strain-mediated chemical potential control of quantum dot self-organization in heteroepitaxy. Phys. Rev. Lett. 92, 025502 (2004).

    Article  Google Scholar 

  22. R. Hull, J. Floro, J. Graham, J. Gray, M. Gherasimova, A. Portavoce, and F.M. Ross: Synthesis and functionalization of epitaxial quantum dot nanostructures for nanoelectronic architectures. Mater. Sci. Semicond. Process. 11, 160–168 (2008).

    Article  CAS  Google Scholar 

  23. M. Gherasimova, R. Hull, M.C. Reuter, and F.M. Ross: Pattern level assembly of Ge quantum dots on Si with focused ion beam templating. Appl. Phys. Lett. 93, 023106 (2008).

    Article  Google Scholar 

  24. J. Kassim, C. Nolph, M. Jamet, P. Reinke, and J. Floro: Ge1−xMnx heteroepitaxial quantum dots: Growth, morphology, and magnetism. J. Appl. Phys. 113, 073910 (2013).

    Article  Google Scholar 

  25. J. Graham, C.D. Kell, J.A. Floro, and R. Hull: Coupled effects of ion beam chemistry and morphology on directed self-assembly of epitaxial semiconductor nanostructures. Nanotechnology 22, 075301 (2011).

    Article  CAS  Google Scholar 

  26. D. Necas and P. Klapetek: Gwyddion: An open-source software for SPM data analysis. Cent. Eur. J. Phys. 10, 181–188 (2012).

    Google Scholar 

  27. A. Portavoce, M. Kammler, R. Hull, M.C. Reuter, and F.M. Ross: Mechanism of the nanoscale localization of Ge quantum dot nucleation on focused ion beam templated Si(001) surfaces. Nanotechnology 17, 4451–4455 (2006).

    Article  CAS  Google Scholar 

  28. D. Grützmacher, C. Dais, L. Zhang, E. Müller, and H.H. Solak: Templated self-organization of SiGe quantum structures for nanoelectronics. Mater. Sci. Eng., C 27, 947–953 (2007).

    Article  Google Scholar 

  29. M. Grydlik, G. Langer, T. Fromherz, F. Schäffler, and M. Brehm: Recipes for the fabrication of strictly ordered Ge islands on pit-patterned Si(001) substrates. Nanotechnology 24, 105601 (2013).

    Article  Google Scholar 

  30. G. Vastola, M. Grydlik, M. Brehm, T. Fromherz, G. Bauer, F. Boioli, L. Miglio, and F. Montalenti: How pit facet inclination drives heteroepitaxial island positioning on patterned substrates. Phys. Rev. B 84, 155415 (2011).

    Article  Google Scholar 

  31. A. Pascale, I. Berbezier, A. Ronda, and P.C. Kelires: Self-assembly and ordering mechanisms of Ge islands on prepatterned Si(001). Phys. Rev. B 77, 075311 (2008).

    Article  Google Scholar 

  32. G. Chen, G. Vastola, H. Lichtenberger, D. Pachinger, G. Bauer, W. Jantsch, F. Schäffler, and L. Miglio: Ordering of Ge islands on hill-patterned Si (001) templates. Appl. Phys. Lett. 92, 113106 (2008).

    Article  Google Scholar 

  33. H. Hu, H.J. Gao, and F. Liu: Theory of directed nucleation of strained islands on patterned substrates. Phys. Rev. Lett. 216102, 2–5 (2008).

    Google Scholar 

  34. J.-N. Aqua and X. Xu: Self-organization vs. directed growth of quantum dots. Phys. Rev. B (2014, accepted).

  35. X. J.-N. Aqua, J. Aqua, and T. Frisch: Growth of a strained epitaxial film on a patterned substrate. Phys. Rev. B 14, (2014, submitted).

  36. X. Xu, J. Aqua, and T. Frisch: Growth kinetics in a strained crystal film on a wavy patterned substrate. J. Phys. Condens. Matter 24, 045002 (2012).

    Article  CAS  Google Scholar 

  37. O. Shklyaev, M. Beck, M. Asta, M. Miksis, and P. Voorhees: Role of strain-dependent surface energies in Ge/Si(100) island formation. Phys. Rev. Lett. 94, 176102 (2005).

    Article  CAS  Google Scholar 

  38. J.A. Floro, E. Chason, S.R. Lee, and G.A. Petersen: Biaxial moduli of coherent Si1−x Gex films on Si (001). Appl. Phys. Lett. 71, 1694 (1997).

    Article  CAS  Google Scholar 

  39. B. Shin and M. Aziz: Modeling RHEED intensity oscillations in multilayer epitaxy: Determination of the Ehrlich-Schwoebel barrier in Ge(001) homoepitaxy. Phys. Rev. B 76, 165408 (2007).

    Article  Google Scholar 

  40. Z-J. Liu and Y.G. Shen: Roughening kinetics of thin films in the presence of both stress and Ehrlich–Schwobel barrier. Appl. Phys. Lett. 83, 5404 (2003).

    Article  CAS  Google Scholar 

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ACKNOWLEDGMENTS

We acknowledge Gopal Ramalingam, Ehsan Monazami Alipour, and Prof. Petra Reinke for their help with key low rate Ge QD growths, and Jean-Noël Aqua for discussions concerning his analysis of growth instabilities on patterned substrates. Funding was generously provided by the II-VI Foundation. Research was performed in part at the Center for Nanoscale Science and Technology (CNST) at the National Institute for Science and Technology (NIST), Gaithersburg, MD, with special thanks to Dr. Joshua Schumacher for his assistance with FIB patterning.

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  1. University of Virginia, Charlottesville, VA, 22904, USA

    Christopher J. Duska & Jerrold A. Floro

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Correspondence to Jerrold A. Floro.

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Duska, C.J., Floro, J.A. Highly uniform arrays of epitaxial Ge quantum dots with interdot spacing of 50 nm. Journal of Materials Research 29, 2240–2249 (2014). https://doi.org/10.1557/jmr.2014.239

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