School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.
Nanoscale and Microscale Research Centre, University of Nottingham, Nottingham NG7 2QL, United Kingdom.
ACS Nano. 2023 Mar 28;17(6):6062-6072. doi: 10.1021/acsnano.3c00670. Epub 2023 Mar 14.
Indium selenides (InSe) have been shown to retain several desirable properties, such as ferroelectricity, tunable photoluminescence through temperature-controlled phase changes, and high electron mobility when confined to two dimensions (2D). In this work we synthesize single-layer, ultrathin, subnanometer-wide InSe by templated growth inside single-walled carbon nanotubes (SWCNTs). Despite the complex polymorphism of InSe we show that the phase of the encapsulated material can be identified through comparison of experimental aberration-corrected transmission electron microscopy (AC-TEM) images and AC-TEM simulations of known structures of InSe. We show that, by altering synthesis conditions, one of two different stoichiometries of sub-nm InSe, namely InSe or β-InSe, can be prepared. Additionally, AC-TEM heating experiments reveal that encapsulated β-InSe undergoes a phase change to γ-InSe above 400 °C. Further analysis of the encapsulated species is performed using X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), energy dispersive X-ray analysis (EDX), and Raman spectroscopy, corroborating the identities of the encapsulated species. These materials could provide a platform for ultrathin, subnanometer-wide phase-change nanoribbons with applications as nanoelectronic components.
硒化铟 (InSe) 被证明保留了多种理想的特性，例如铁电性、通过温度控制的相变化可调的光致发光以及在限制为二维时的高电子迁移率。在这项工作中，我们通过在单壁碳纳米管 (SWCNT) 内模板生长合成了单层、超薄、亚纳米宽的 InSe。尽管 InSe 的多晶型性很复杂，但我们通过比较实验校正像差的透射电子显微镜 (AC-TEM) 图像和已知 InSe 结构的 AC-TEM 模拟，证明了封装材料的相可以被识别。我们表明，通过改变合成条件，可以制备两种不同化学计量比的亚纳米 InSe 中的一种，即 InSe 或β-InSe。此外，AC-TEM 加热实验表明，封装的β-InSe 在 400°C 以上会发生向γ-InSe 的相转变。使用 X 射线光电子能谱 (XPS)、热重分析 (TGA)、能谱分析 (EDX) 和拉曼光谱对封装物种进行了进一步分析，证实了封装物种的身份。这些材料可以为具有应用于纳米电子元件的超薄、亚纳米宽相变纳米带提供平台。
