为了实现紫外-可见波段的高响应度/低成本的广光谱光电探测,我们制备了基于一维p型Se微米线与二维n型InSe纳米片的混维范德瓦尔斯异质结广光谱探测器。得益于Se微米线与二维层状结构InSe纳米片的高结晶质量, 该器件在紫外-可见光广光谱范围都具有非常高的响应度, 该器件的响应截止边为700 nm。 值得指出的是, 该器件在-5 V的偏压下, 对460 nm的光源响应度可以达到108 mA/W,该数值比原来的Se探测器高了800%。这项研究有利于拓展我们对范德瓦尔斯异质结的认识, 也为今后制备高性能的低维光电探测器提供了一种新的途径。

Phonon is one of the most important elementary excitations, and is fundamental for understanding thermodynamic properties, such as heat capacity, Debye temperature, and the coefficient of thermal expansion. Furthermore, electron-phonon coupling can determine the electric conductivity and superconductivity of materials. Raman spectroscopy is the most important tool to study phonon physics, and can not only be utilized to explore the lattice structure and quality of materials but also their phonon properties, electronic band structure and electron-phonon coupling. Here, we investigate the phonon physics of two-dimensional (2D) materials and the related van der Waals heterostructures by Raman spectroscopy. First, we will introduce interlayer and intralayer phonon modes. The frequency of the interlayer phonon modes can be well reproduced by the linear chain model while their intensity can be calculated by the interlayer bond polarizability model; in addition, the splitting frequency between Davydov components in multilayer 2D materials originating from the same intralayer mode in monolayer counterpart can be well fitted by the van der Waals model. Secondly, we extend these models to 2D van der Waals heterostructures. By taking twisted multilayer graphene, MoS2/graphene and hBN/WS2 heterostructures as examples, we demonstrate how to calculate the frequency and Raman intensity of the interlayer modes by the linear chain and interlayer polarizability models, respectively, which can further give the strength of the interlayer coupling and electron-phonon coupling for layer-breathing modes in van der Waals heterostructures.