论文标题
I $ _3 $ -Type基底堆叠故障的与生长相关的形成机制在外延生长的六边形GE-2H
Growth-related formation mechanism of I$_3$-type basal stacking fault in epitaxially grown hexagonal Ge-2H
论文作者
论文摘要
GE的六边形-2H晶体阶段最近在中红外范围内成为有希望的直接带隙半导体，为组IV半导体（GE和SIGE）提供了额外的光电功能的新前景。这种六角形（2H）GE相的受控合成是一个挑战，可以通过使用Wurtzite Gaas纳米线作为模板来克服。但是，根据生长条件，I $ _3 $ -Type的异常基础堆叠断层（BSF）在亚稳态2H结构中形成。使用化学蒸气沉积，通过环境传输电子显微镜实时观察到这种核/壳异质结构的生长。这些观察结果提供了GE-2H表层逐步增长的直接证据，并揭示了在不稳定增长期间与I $ _3 $ -BSF的增长相关的形成。他们的形成条件正在动态研究。通过这些原位观察，我们可以提出一个场景，以实现I $ _3 $ -Type BSF的成核，这可能对任何在M-Plane底物上生长的稳定六角形2H或Wurtzite结构有效。确定条件以避免其形成以完美的晶体合成SIGE-2H。
The hexagonal-2H crystal phase of Ge recently emerged as a promising direct bandgap semiconductor in the mid-infrared range providing new prospects of additional optoelectronic functionalities of group-IV semiconductors (Ge and SiGe). The controlled synthesis of such hexagonal (2H) Ge phase is a challenge that can be overcome by using wurtzite GaAs nanowires as a template. However, depending on growth conditions, unusual basal stacking faults (BSFs) of I$_3$-type are formed in the metastable 2H structure. The growth of such core/shell heterostructures is observed in situ and in real-time by means of environmental transmission electron microscopy using chemical vapour deposition. The observations provide direct evidence of a step-flow growth of Ge-2H epilayers and reveal the growth-related formation of I$_3$-BSF during unstable growth. Their formation conditions are dynamically investigated. Through these in situ observations, we can propose a scenario for the nucleation of I$_3$-type BSFs that is likely valid for any metastable hexagonal 2H or wurtzite structures grown on m-plane substrates. Conditions are identified to avoid their formation for perfect crystalline synthesis of SiGe-2H.
