成核
分子束外延
材料科学
薄膜
岛屿生长
基质(水族馆)
外延
凝聚态物理
聚结(物理)
单层
图层(电子)
化学物理
光电子学
纳米技术
化学
物理
地质学
海洋学
有机化学
天体生物学
作者
A. Elbaroudy,Bohdan Khromets,F. Sfigakis,E. Bergeron,Yao Shi,Man Chun Tam,George Nichols,T. Blaikie,Jonathan Baugh,Z. R. Wasilewski
出处
期刊:Journal of vacuum science & technology
[American Vacuum Society]
日期:2024-04-16
卷期号:42 (3)
摘要
Among superconductor/semiconductor hybrid structures, in situ aluminum (Al) grown on InGaAs/InAs is widely pursued for the experimental realization of Majorana Zero Mode quasiparticles. This is due to the high carrier mobility, low effective mass, and large Landé g-factor of InAs, coupled with the relatively high value of the in-plane critical magnetic field in thin Al films. However, growing a thin, continuous Al layer using the molecular beam epitaxy (MBE) is challenging due to aluminum's high surface mobility and tendency for 3D nucleation on semiconductor surfaces. A study of epitaxial Al thin film growth on In0.75Ga0.25As with MBE is presented, focusing on the effects of the Al growth rate and substrate temperature on the nucleation of Al layers. We find that for low deposition rates, 0.1 and 0.5 Å/s, the growth continues in 3D mode during the deposition of the nominal 100 Å of Al, resulting in isolated Al islands. However, for growth rates of 1.5 Å/s and above, the 3D growth mode quickly transitions into island coalescence, leading to a uniform 2D Al layer. Moreover, this transition is very abrupt, happening over an Al flux increase of less than 1%. We discuss the growth mechanisms explaining these observations. The results give new insights into the kinetics of Al deposition and show that with sufficiently high Al flux, a 2D growth on substrates at close to room temperature can be achieved already within the first few Al monolayers. This eliminates the need for complex cryogenic substrate cooling and paves the way for the development of high-quality superconductor-semiconductor interfaces in standard MBE systems.
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