One-Step Synthesis of Non-Layered 2D Bi2WO6 Nanosheets for electronics and optoelectronics

Since the discovery of graphene, two-dimensional (2D) materials have been a research hotspot. 2D semiconductor materials, with their atomic-level thickness and excellent electronic and optoelectronic properties, are considered ideal semiconductor materials. However, van der Waals materials account for only 5% of the crystal structure database, resulting in a limited number of 2D materials to be studied, which restricts their development and application. The development of non-van der Waals 2D materials will greatly enrich the family of 2D semiconductor materials. However, the two-dimensional growth of non-van der Waals materials remains a significant challenge, as conventional synthesis methods struggle to limit their growth in three dimensions. This study developed a one-step chemical vapor deposition method to grow non-van der Waals 2D Bi2WO6 nanosheets on C-plane sapphire with an average size of 60 μm. Furthermore, the thickness of the 2D Bi2WO6 nanosheets was precisely controlled by adjusting the growth parameters. The Bi2WO6 nanosheets were used to construct a top-gate FET, achieving an on/off ratio as high as 106 and a carrier mobility of 2.4 cm2∙V-1∙s-1. This study also constructed a photodetector that achieved a specific detectivity of up to 3.6 × 1010, a responsivity of 0.779 A·W-1, and an EQE of 218.5%. This research demonstrates that 2D Bi2WO6 holds promise as an ideal material for future electronic and optoelectronic devices.

自石墨烯被发现以来，二维（2D）材料一直是科研领域的热点方向。二维半导体材料凭借原子级厚度以及优异的电子与光电性能，被视为理想的半导体材料。然而，范德瓦尔斯（van der Waals）材料仅占晶体结构数据库的5%，可研究的二维材料数量有限，这制约了其发展与应用。非范德瓦尔斯二维材料的开发将极大丰富二维半导体材料家族。然而，非范德瓦尔斯材料的二维生长仍面临重大挑战，传统合成方法难以限制其三维生长。本研究开发了一种一步化学气相沉积法，在C面蓝宝石衬底上生长出非范德瓦尔斯二维Bi₂WO₆纳米片，其平均尺寸可达60 μm。此外，通过调控生长参数，可精准控制二维Bi₂WO₆纳米片的厚度。本研究使用Bi₂WO₆纳米片构建了顶栅场效应晶体管（top-gate FET），实现了高达10⁶的开关比以及2.4 cm²·V⁻¹·s⁻¹的载流子迁移率。本研究还构建了一款光电探测器，其比探测率最高可达3.6×10¹⁰，响应度达0.779 A·W⁻¹，外量子效率（External Quantum Efficiency, EQE）为218.5%。本研究表明，二维Bi₂WO₆有望成为未来电子与光电设备的理想材料。