Hunan Provincial Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan 411105, People's Republic of China.
Nanoscale. 2018 Sep 13;10(35):16759-16764. doi: 10.1039/c8nr04660c.
A thickness dependent band gap is commonly found in layered two-dimensional (2D) materials. Here, using a C3N bilayer as a prototypical model, we systematically investigated the evolution of a band gap from a single layer to a bilayer using first principles calculations and tight binding modeling. We show that in addition to the widely known effect of interlayer hopping, de-charge transfer also plays an important role in tuning the band gap. The de-charge transfer is defined with reference to the charge states of atoms in the single layer without stacking, which shifts the energy level and modifies the band gap. Together with band edge splitting induced by the interlayer hopping, the energy level shifting caused by the de-charge transfer determines the size of the band gap in bilayer C3N. Our finding, applicable to other 2D semiconductors, provides an alternative approach for realizing band gap engineering in 2D materials.
在层状二维（2D）材料中，通常会发现一个与厚度相关的能隙。在这里，我们使用 C3N 双层作为典型模型，通过第一性原理计算和紧束缚建模系统地研究了从单层到双层的能带隙的演化。我们表明，除了广泛存在的层间跃迁效应之外，去电荷转移也在调节能带隙方面起着重要作用。去电荷转移是参照没有堆叠的单层原子的电荷状态来定义的，它会改变能级并改变能带隙。与由层间跃迁引起的能带边缘劈裂相结合，由去电荷转移引起的能级移动决定了双层 C3N 的能带隙大小。我们的发现适用于其他 2D 半导体，为在 2D 材料中实现能带工程提供了一种替代方法。
