State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing, 100084, China.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082, China.
Adv Mater. 2017 Oct;29(39). doi: 10.1002/adma.201702942. Epub 2017 Aug 21.
Van der Waals (vdW) heterostructures have received intense attention for their efficient stacking methodology with 2D nanomaterials in vertical dimension. However, it is still a challenge to scale down the lateral size of vdW heterostructures to the nanometer and make proper contacts to achieve optimized performances. Here, a carbon-nanotube-confined vertical heterostructure (CCVH) is employed to address this challenge, in which 2D semiconductors are asymmetrically sandwiched by an individual metallic single-walled carbon nanotube (SWCNT) and a metal electrode. By using WSe and MoS , the CCVH can be made into p-type and n-type field effect transistors with high on/off ratios even when the channel length is 3.3 nm. A complementary inverter was further built with them, indicating their potential in logic circuits with a high integration level. Furthermore, the Fermi level of SWCNTs can be efficiently modulated by the gate voltage, making it competent for both electron and hole injection in the CCVHs. This unique property is shown by the transition of WSe CCVH from unipolar to bipolar, and the transition of WSe /MoS from p-n junction to n-n junction under proper source-drain biases and gate voltages. Therefore, the CCVH, as a member of 1D/2D mixed heterostructures, shows great potentials in future nanoelectronics and nano-optoelectronics.
范德华 (vdW) 异质结构因其在垂直方向上与二维纳米材料堆叠的高效方法而受到广泛关注。然而，将 vdW 异质结构的横向尺寸缩小到纳米级并进行适当的接触以实现优化性能仍然是一个挑战。在这里，采用碳纳米管限制的垂直异质结构 (CCVH) 来解决这一挑战，其中二维半导体被单个金属单壁碳纳米管 (SWCNT) 和金属电极不对称地夹在中间。通过使用 WSe 和 MoS ，CCVH 可以制成具有高导通/关断比的 p 型和 n 型场效应晶体管，即使通道长度为 3.3nm 也是如此。进一步用它们构建了互补型反相器，表明它们在具有高集成度的逻辑电路中有潜力。此外，SWCNTs 的费米能级可以通过栅极电压有效地进行调制，这使其能够在 CCVHs 中进行电子和空穴注入。这种独特的特性表现在 WSe CCVH 从单极到双极的转变，以及在适当的源极-漏极偏置和栅极电压下，WSe /MoS 从 p-n 结到 n-n 结的转变。因此，CCVH 作为 1D/2D 混合异质结构的一员，在未来的纳米电子学和纳米光电学中具有巨大的潜力。
