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首页> 外文期刊>Physical review >Atomic processes in molecular beam epitaxy on strained InAs(137): A density-functional theory study
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Atomic processes in molecular beam epitaxy on strained InAs(137): A density-functional theory study

机译：应变InAs（137）上分子束外延的原子过程：密度泛函理论研究

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摘要

The atomic processes in molecular beam epitaxy of In As on the InAs(137) surface are investigated by means of first-principles total-energy calculations. We consider layer-by-layer growth on InAs(137) facets as a typical process during the evolution of shallow InAs islands in the Stranski-Krastanov growth mode of InAs on GaAs that is exploited for the self-assembly of heteroepitaxial quantum dots. From the calculated energetics we conclude that a growth scenario where an As_2 molecule adsorbs on a single In adatom, followed by capture of another In adatom, is most likely. Moreover, our calculations of the potential-energy surface for In adatoms on the InAs(137) surface show that In adatoms are highly mobile. Surface diffusion on InAs(137) is found to be almost isotropic with energy barriers <0.3 eV for adatom hopping. Aiming at an understanding of the growth processes at the strained side facets of quantum dots, we extend our calculations to isotropically strained InAs(137) facets. It is found that the compressive strain present on side facets of shallow InAs islands on GaAs leads to a considerable lowering of the binding energy of In adatoms. The height of diffusion barriers is found to be less affected by the strain. Most importantly, the intermediate species consisting of an In adatom plus an adsorbed As_2 molecule is destabilized by compressive strain in excess of -5%. This finding leads us to the conclusion that layer growth on InAs(137) facets ceases in highly strained regions of InAs islands on GaAs, in line with the observed shape evolution of such islands.
机译：通过第一性原理的总能计算，研究了InAs（137）表面上In As分子束外延中的原子过程。我们将InAs（137）面上的逐层生长视为GaAs上InAs的Stranski-Krastanov生长模式中浅InAs岛演化过程中的典型过程，该生长模式用于异质外延量子点的自组装。从计算得出的能量学中，我们得出结论，最有可能出现As_2分子吸附在单个In吸附原子上，然后捕获另一个In吸附原子的生长情况。此外，我们对InAs（137）表面上In原子的势能面的计算表明In原子是高度可移动的。发现InAs（137）上的表面扩散几乎是各向同性的，对于原子跳跃而言，能垒<0.3 eV。为了了解量子点应变侧面上的生长过程，我们将计算扩展到各向同性应变的InAs（137）面上。发现存在于GaAs上的浅InAs岛的侧面上的压缩应变导致In吸附原子的结合能显着降低。发现扩散势垒的高度受应变的影响较小。最重要的是，由In原子加上吸附的As_2分子组成的中间物种因超过-5％的压缩应变而不稳定。这一发现使我们得出结论，即在GaAs上InAs岛的高度应变区域中，InAs（137）小面上的层生长停止了，这与观察到的岛的形状演变一致。

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  • 来源
    《Physical review》 |2009年第3期|035324.1-035324.7|共7页
  • 作者

    P. Kratzer; T. Hammerschmidt;

  • 作者单位

    Fakultaet fuer Physik, and Center for Nanointegration (CeNIDE), Universitaet Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany;

    Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universitaet Bochum, Stiepeler Strasse 129, D-44801 Bochum, Germany;

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  • 关键词

    diffusion of adsorbates; kinetics of coarsening and aggregation; Ⅲ-Ⅴ semiconductors; quantum dots;

    机译：吸附物的扩散;粗化和聚集的动力学;Ⅲ-Ⅴ族半导体;量子点;

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