Vertical composition gradient in InGaAs/GaAs alloy quantum dots as revealed by high-resolution x-ray diffraction

Hanke, M.; Grigoriev, D.; Schmidbauer, M.; Schäfer, P.; Köhler, R.; Sellin, R. L.; Pohl, U. W.; Bimberg, D.
October 2004
Applied Physics Letters;10/11/2004, Vol. 85 Issue 15, p3062
Academic Journal
Shape and composition profiles of self-organized In0.6Ga0.4As/GaAs quantum dots (QDs) were investigated using diffuse x-ray scattering of a fivefold QD stack. To reveal the QD morphology, numerical scattering simulations of QDs with different morphologies were performed based on three-dimensional strain fields calculated by the finite element methods. Comparing our simulations to the data, we proved that the In concentration increases from the wetting layer to the top of the quantum dots. Moreover, we conclude that the In concentration of the wetting layers is significantly lower than the average value in the QDs.


Related Articles

  • High optical sensitivity to ambient conditions of uncapped InGaAs surface quantum dots. Milla, M. J.; Ulloa, J. M.; Guzmán, A. // Applied Physics Letters;3/26/2012, Vol. 100 Issue 13, p131601 

    The influence of the environment on the optical properties of self-assembled In0.5Ga0.5As surface quantum dots is studied as a function of different ambient conditions for sensing applications. Their room temperature photoluminescence (PL) quenches under vacuum and decreases strongly under dry...

  • Initial stages of chain formation in a single layer of (In,Ga)As quantum dots grown on GaAs (100). Schmidbauer, M.; Wang, Zh. M.; Mazur, Yu. I.; Lytvyn, P. M.; Salamo, G. J.; Grigoriev, D.; Schäfer, P.; Köhler, R.; Hanke, M. // Applied Physics Letters;8/27/2007, Vol. 91 Issue 9, p093110 

    The self-organized formation of In0.40Ga0.60As quantum dot chains was investigated using x-ray scattering. Two samples were compared grown on GaAs(100) by molecular beam epitaxy. The first sample with a single layer of In0.40Ga0.60As dots shows weak quantum dot alignment and a corresponding...

  • Nanovoids in InGaAs/GaAs quantum dots observed by cross-sectional scanning tunneling microscopy. Lenz, A.; Eisele, H.; Timm, R.; Becker, S. K.; Sellin, R. L.; Pohl, U. W.; Bimberg, D.; Dähne, M. // Applied Physics Letters;10/25/2004, Vol. 85 Issue 17, p3848 

    We present cross-sectional scanning tunneling microscopy data of a type of InGaAs/GaAs quantum-dot structure characterized by a hollow center. This void structure develops during a long growth interruption applied after deposition of a quantum dot layer and a thin cap layer, resulting in an...

  • Cleaved-edge overgrowth of aligned quantum dots on strained layers of InGaAs. Wasserman, D.; Lyon, S. A. // Applied Physics Letters;11/29/2004, Vol. 85 Issue 22, p5352 

    Strain aligned InAs quantum dots were grown on the cleaved edges of first growth samples containing strained InxGa(1-x)As layers of varying thickness and indium fraction. The formation of the cleaved-edge quantum dots was observed by means of atomic force microscopy. 100% linear alignment of...

  • The Thermal Model for Carrier Hopping and Retrapping in Self-Organized InAs Quantum Dot Heterostructure. Ya-Fen Wu; Hui-Tang Shen; Ray-Min Lin; Tzer-En Nee; Nien-Tze Yeh; Hsieh, Tung-Po; Lee, Jiunn-Chyi // AIP Conference Proceedings;2005, Vol. 772 Issue 1, p647 

    A steady-state thermal model based on a set of rate equations is proposed in this article. The carrier dynamics of the main components in quantum dot (QD) systems, including the intersublevels in InAs QDs, the wetting layer, and the GaAs barriers, are all described by the equations. The QD sizes...

  • Capacitance spectroscopy study of InAs quantum dots and dislocations in p-GaAs matrix. Brunkov, P. N.; Monakhov, E. V.; Kuznetsov, A. Yu.; Gutkin, A. A.; Bobyl, A. V.; Musikhin, Yu. G.; Zhukov, A. E.; Ustinov, V. M.; Konnikov, S. G. // AIP Conference Proceedings;2005, Vol. 772 Issue 1, p789 

    Two hole traps have been identified in epitaxially grown n+-p-GaAs diodes with embedded self organized InAs quantum dots using temperature dependent capacitance-voltage (C-V) measurement, admittance spectroscopy and deep level transient spectroscopy (DLTS). One trap is found to be located in the...

  • Carrier spin dynamics in modulation-doped InAs/GaAs quantum dots. Marcinkevicˇius, S.; Siegert, J.; Zhao, Q. X. // Journal of Applied Physics;9/1/2006, Vol. 100 Issue 5, p054310 

    Photoexcited electron and hole spin relaxation was studied in modulation-doped and undoped InAs/GaAs quantum dots by means of time-resolved photoluminescence. After excitation into the barriers or the wetting layer, the electron spin polarization is preserved during the capture and relaxation in...

  • Photoluminescence from seeded three-dimensional InAs/GaAs quantum-dot crystals. Kiravittaya, S.; Rastelli, A.; Schmidt, O. G. // Applied Physics Letters;1/23/2006, Vol. 88 Issue 4, p043112 

    We investigate the photoluminescence (PL) properties of three-dimensional InAs/GaAs quantum-dot (QD) crystals grown on shallow modulated periodic hole arrays patterned on GaAs(001). We find that the PL spectra become narrower and more intense with increasing number of QD layers. A deconvoluted...

  • Ultrafast carrier capture and relaxation in modulation-doped InAs quantum dots. Sun, K. W.; Kechiantz, A.; Lee, B. C.; Lee, C. P. // Applied Physics Letters;4/17/2006, Vol. 88 Issue 16, p163117 

    We report investigations on carrier capture and relaxation processes in undoped and modulation-doped InAs/GaAs self-assembled quantum dots (QDs) by using time-resolved spectroscopy technique with a time resolution of ∼200 fs. We find that carrier capture and relaxation in the ground state...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics