南开大学吴金雄团队报道了成分可调的高κ性能可转移超薄Bi₂Ge(Si)O₅介电合金的可控合成。相关研究成果发表在2024年4月14日出版的国际学术期刊《美国化学会杂志》。

二维（2D）合金有望成为2D晶体管的重要部件，因为它们的特性能够通过改变其成分进行连续调节。然而，以前的研究主要局限于作为接触/沟道材料的金属/半导体材料，但很少与绝缘电介质有关。

该文中，研究人员使用一种简单的一步化学气相沉积（CVD）方法来合成超薄Bi₂Si_xGe_1–xO₅介电合金，其成分仅通过改变GeO₂/SiO₂前体的相对比例就可以在整个x范围内进行调整。此外，它们的介电性质是高度组分可调的，在CVD生长的2D绝缘体中显示出>40的创纪录的高介电常数。

Bi₂GeO₅和Bi₂Si_xGe_1–xO₅的垂直生长特性使聚合物自由转移和随后的清洁范德华集成为高κ封装层，以增强2D半导体的迁移率。此外，使用Bi₂Si_xGe_1–xO₅合金作为栅极电介质的MoS₂晶体管表现出大的I_on/I_off（>10⁸）、～61mV/decade的理想亚阈值摆动和较小的栅极磁滞（～5mV）。

该工作不仅给出了很少的绝缘介质合金可控CVD生长的例子，而且扩展了2D单晶高κ电介质的家族。

附：英文原文

Title: Controllable Synthesis of Transferable Ultrathin Bi2Ge(Si)O5 Dielectric Alloys with Composition-Tunable High-κ Properties

Author: Jiabiao Chen, Zhaochao Liu, Zunxian Lv, Yameng Hou, Xiang Chen, Lan Lan, Tong-Huai Cheng, Lei Zhang, Yingnan Duan, Huixia Fu, Xuewen Fu, Feng Luo, Jinxiong Wu

Issue&Volume: April 14, 2024

Abstract: Two-dimensional (2D) alloys hold great promise to serve as important components of 2D transistors, since their properties allow continuous regulation by varying their compositions. However, previous studies are mainly limited to the metallic/semiconducting ones as contact/channel materials, but very few are related to the insulating dielectrics. Here, we use a facile one-step chemical vapor deposition (CVD) method to synthesize ultrathin Bi2SixGe1–xO5 dielectric alloys, whose composition is tunable over the full range of x just by changing the relative ratios of the GeO2/SiO2 precursors. Moreover, their dielectric properties are highly composition-tunable, showing a record-high dielectric constant of >40 among CVD-grown 2D insulators. The vertically grown nature of Bi2GeO5 and Bi2SixGe1–xO5 enables  polymer-free transfer and subsequent clean van der Waals integration as the high-κ encapsulation layer to enhance the mobility of 2D semiconductors. Besides, the MoS2 transistors using Bi2SixGe1–xO5 alloy as gate dielectrics exhibit a large Ion/Ioff (>108), ideal subthreshold swing of ～61 mV/decade, and a small gate hysteresis (～5 mV). Our work not only gives  very few examples on controlled CVD growth of insulating dielectric alloys but also expands the family of 2D single-crystalline high-κ dielectrics.

DOI: 10.1021/jacs.4c02496

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c02496