Lin Yuxuan, Ma Qiong, Shen Pin-Chun, Ilyas Batyr, Bie Yaqing, Liao Albert, Ergeçen Emre, Han Bingnan, Mao Nannan, Zhang Xu, Ji Xiang, Zhang Yuhao, Yin Jihao, Huang Shengxi, Dresselhaus Mildred, Gedik Nuh, Jarillo-Herrero Pablo, Ling Xi, Kong Jing, Palacios Tomás
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sci Adv. 2019 Jun 14;5(6):eaav1493. doi: 10.1126/sciadv.aav1493. eCollection 2019 Jun.
The massless Dirac electron transport in graphene has led to a variety of unique light-matter interaction phenomena, which promise many novel optoelectronic applications. Most of the effects are only accessible by breaking the spatial symmetry, through introducing edges, p-n junctions, or heterogeneous interfaces. The recent development of direct synthesis of lateral heterostructures offers new opportunities to achieve the desired asymmetry. As a proof of concept, we study the photothermoelectric effect in an asymmetric lateral heterojunction between the Dirac semimetallic monolayer graphene and the parabolic semiconducting monolayer MoS. Very different hot-carrier cooling mechanisms on the graphene and the MoS sides allow us to resolve the asymmetric thermalization pathways of photoinduced hot carriers spatially with electrostatic gate tunability. We also demonstrate the potential of graphene-2D semiconductor lateral heterojunctions as broadband infrared photodetectors. The proposed structure shows an extreme in-plane asymmetry and provides a new platform to study light-matter interactions in low-dimensional systems.
石墨烯中无质量狄拉克电子输运引发了各种独特的光与物质相互作用现象，这预示着许多新颖的光电子应用。大多数效应只有通过引入边缘、p-n结或异质界面来打破空间对称性才能实现。横向异质结构直接合成技术的最新进展为实现所需的不对称性提供了新机遇。作为概念验证，我们研究了狄拉克半金属单层石墨烯与抛物线型半导体单层MoS₂之间的不对称横向异质结中的光热电效应。石墨烯和MoS₂两侧截然不同的热载流子冷却机制使我们能够通过静电栅极可调性在空间上分辨光致热载流子的不对称热化路径。我们还展示了石墨烯-二维半导体横向异质结作为宽带红外光电探测器的潜力。所提出的结构表现出极端的面内不对称性，并为研究低维系统中的光与物质相互作用提供了一个新平台。
