Balakirev Sergey V, Solodovnik Maxim S, Eremenko Mikhail M, Chernenko Natalia E, Ageev Oleg A
Department of Nanotechnologies and Microsystems, Institute of Nanotechnologies, Electronics and Equipment Engineering, Southern Federal University, Taganrog 347922, Russia.
Nanotechnology. 2020 Nov 27;31(48):485604. doi: 10.1088/1361-6528/abb15e.
Semiconductor quantum dots (QDs) in the InAs/AlGaAs system are of great importance due to their promising optoelectronic and nanophotonic applications. However, control over emission wavelength governed by Al content in the matrix is still limited because of an influence of surface Al content on QD size and density. In this paper, we study the growth of In nanostructures by droplet epitaxy on various AlGaAs surfaces. We demonstrate that an increase in the Al content leads to a decrease in the droplet density and an increase in their size, which contradicts the Stranski-Krastanov QD growth. Using a hybrid analytical-Monte Carlo model, we explain this phenomenon by the fact that In adatoms acquire higher mobility on a first indium monolayer which is bound to surface Al atoms. This assumption is confirmed by the fact that a temperature decrease does not lead to a great increase in the critical thickness of droplet formation on the Al-containing surfaces whereas it changes considerably on the GaAs surface. Furthermore, the Al content influence on the formation of In droplets is much less significant than on the growth of InAs QDs by the Stranski-Krastanov mode. This gives an opportunity to use droplet epitaxy to control the matrix bandgap without considerable influence on the QD characteristics.
InAs/AlGaAs体系中的半导体量子点（QDs）因其在光电子和纳米光子学方面的应用前景而具有重要意义。然而，由于表面Al含量对量子点尺寸和密度的影响，由基质中Al含量控制的发射波长的调控仍然有限。在本文中，我们研究了通过液滴外延在各种AlGaAs表面上生长In纳米结构。我们证明，Al含量的增加导致液滴密度降低和尺寸增大，这与Stranski-Krastanov量子点生长情况相反。使用混合解析-蒙特卡罗模型，我们通过In吸附原子在与表面Al原子结合的第一个铟单层上具有更高迁移率这一事实来解释这种现象。这一假设得到了以下事实的证实：温度降低不会导致含Al表面上液滴形成的临界厚度大幅增加，而在GaAs表面上则有很大变化。此外，Al含量对In液滴形成的影响远不如对通过Stranski-Krastanov模式生长InAs量子点的影响显著。这使得利用液滴外延来控制基质带隙而不对量子点特性产生显著影响成为可能。
