State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China.
Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China.
Nano Lett. 2019 Mar 13;19(3):1632-1642. doi: 10.1021/acs.nanolett.8b04561. Epub 2019 Feb 27.
Low-dimensional narrow-band-gap III-V semiconductors are key building blocks for the next generation of high-performance nanoelectronics, nanophotonics, and quantum devices. Realizing these various applications requires an efficient methodology that enables the material dimensional control during the synthesis process and the mass production of these materials with perfect crystallinity, reproducibility, low cost, and outstanding electronic and optoelectronic properties. Although advances in one- and two-dimensional narrow-band-gap III-V semiconductors synthesis, the progress toward reliable methods that can satisfy all of these requirements has been limited. Here, we demonstrate an approach that provides a precise control of the dimension of InAs from one-dimensional nanowires to wafer-scale free-standing two-dimensional nanosheets, which have a high degree of crystallinity and outstanding electrical and optical properties, using molecular-beam epitaxy by controlling catalyst alloy segregation. In our approach, two-dimensional InAs nanosheets can be obtained directly from one-dimensional InAs nanowires by silver-indium alloy segregation, which is much easier than the previously reported methods, such as the traditional buffering technique and select-area epitaxial growth. Detailed transmission electron microscopy investigations provide solid evidence that the catalyst alloy segregation is the origination of the InAs dimensional transformation from one-dimensional nanowires to two-dimensional nanosheets and even to three-dimensional complex crosses. Using this method, we find that the wafer-scale free-standing InAs nanosheets can be grown on various substrates including Si, MgO, sapphire, GaAs, etc. The InAs nanosheets grown at high temperature are pure-phase single crystals and have a high electron mobility and a long time-resolved terahertz kinetics lifetime. Our work will open up a conceptually new and general technology route toward the effective controlling of the dimension of the low-dimensional III-V semiconductors. It may also enable the low-cost fabrication of free-standing nanosheet-based devices on an industrial scale.
低维窄带隙 III-V 半导体是下一代高性能纳电子学、纳米光子学和量子器件的关键构建块。实现这些各种应用需要一种有效的方法，该方法能够在合成过程中实现材料的维度控制，并能够大规模生产具有完美结晶度、可重复性、低成本和出色的电子和光电性能的这些材料。尽管在一维和二维窄带隙 III-V 半导体合成方面取得了进展，但能够满足所有这些要求的可靠方法的进展一直受到限制。在这里，我们展示了一种通过控制催化剂合金分凝来精确控制 InAs 尺寸的方法，从一维纳米线到晶圆级的独立二维纳米片，这些二维纳米片具有高度的结晶度和出色的电学和光学性能，使用分子束外延。在我们的方法中，二维 InAs 纳米片可以通过银铟合金分凝直接从一维 InAs 纳米线获得，这比以前报道的方法（例如传统的缓冲技术和选择区域外延生长）容易得多。详细的透射电子显微镜研究提供了确凿的证据，证明催化剂合金分凝是一维纳米线到二维纳米片甚至三维复杂交叉的 InAs 尺寸转变的起源。使用这种方法，我们发现晶圆级独立的 InAs 纳米片可以在包括 Si、MgO、蓝宝石、GaAs 等各种衬底上生长。在高温下生长的 InAs 纳米片是纯相单晶，具有高电子迁移率和长时间分辨太赫兹动力学寿命。我们的工作将开辟一条全新的、通用的技术路线，以有效地控制低维 III-V 半导体的尺寸。它还可能使基于独立纳米片的器件在工业规模上以低成本制造。
