Dong Xiansheng, Chen Tong, Liu Guogang, Xie Luzhen, Zhou Guanghui, Long Mengqiu
School of Energy and Mechanical Engineering, Energy Materials Computing Center, Jiangxi University of Science and Technology, Nanchang330013, China.
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai200433, P. R. China.
ACS Sens. 2022 Nov 25;7(11):3450-3460. doi: 10.1021/acssensors.2c01785. Epub 2022 Nov 7.
Two-dimensional (2D) magnetic materials are the key to the development of the new generation in spintronics technology and engineering multifunctional devices. Herein, the electronic, spin-resolved transmission, and gas sensing properties of the 2D g-CN/MoS van der Waals (vdW) heterostructure have been investigated by using density functional theory with non-equilibrium Green's function method. First, the g-CN/MoS vdW heterostructure demonstrates ferromagnetic half-metallicity and superior adsorption capacity for gas molecules. The spin-dependent electronic transport of the g-CN/MoS-based nanodevice is obviously regulated by parallel or anti-parallel spin configuration in electrodes, leading to perfect single-spin conduction behavior with a nearly 100% spin filtering efficiency, a negative differential resistance effect, and other interesting electrical transport phenomena. Moreover, g-CN/MoS exhibits directional dependency and strong transport anisotropic behavior under bias windows, indicating that the electric current propagates more easily through the vertical direction than the horizontal direction. The physical mechanisms are revealed and analyzed by presenting the bias-dependent transmission spectra in combination with the projected local device density of states. Finally, the g-CN/MoS-based gas sensor is more sensitive to CO, NO, NO, and NH molecules with the chemisorption type. The strong chemical adsorption leads to the formation of electrons on the local scattering center and ultimately affects the transport properties, resulting in the maximum gas sensitivity reaching 6.45 for NO at the bias of 0.8 V. This work not only reveals that the g-CN/MoS vdW heterostructure with high anisotropy, perfect spin filtering, and outstanding gas sensitivity is a promising 2D material but also provides an insight into the further application in futuristic electronic nanodevices.
二维（2D）磁性材料是自旋电子学技术和工程多功能器件新一代发展的关键。在此，通过使用非平衡格林函数方法的密度泛函理论，研究了二维g-CN/MoS范德华（vdW）异质结构的电子、自旋分辨传输和气体传感特性。首先，g-CN/MoS vdW异质结构表现出铁磁半金属性和对气体分子的优异吸附能力。基于g-CN/MoS的纳米器件的自旋相关电子输运明显受到电极中平行或反平行自旋构型的调节，导致具有近100%自旋过滤效率、负微分电阻效应和其他有趣的电输运现象的完美单自旋传导行为。此外，g-CN/MoS在偏置窗口下表现出方向依赖性和强传输各向异性行为，表明电流在垂直方向上比在水平方向上更容易传播。通过结合投影局部器件态密度给出偏置相关的传输光谱，揭示并分析了其物理机制。最后，基于g-CN/MoS的气体传感器对具有化学吸附类型的CO、NO、NO和NH分子更为敏感。强化学吸附导致在局部散射中心形成电子，最终影响传输特性，在0.8 V偏置下，NO的最大气体灵敏度达到6.45。这项工作不仅揭示了具有高各向异性、完美自旋过滤和出色气体灵敏度的g-CN/MoS vdW异质结构是一种有前途的二维材料，而且为其在未来电子纳米器件中的进一步应用提供了见解。
