期刊
JOURNAL OF PHYSICS-CONDENSED MATTER
卷 31, 期 11, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1361-648X/aafd12
关键词
van der Waals heterojunction; interlayer exciton; MoS2; GaSe; 2D p-n junction; optoelectronics; density functional theory
资金
- DFG Research Unit [FOR 1497, FOR 1713]
- DFG Cluster of Excellence CFAED (Center for Advancing Electronics Dresden)
- Helmholtz Initiative and Networking Funds [W2/W3-026]
Two dimensional (2D) semiconductors feature exceptional optoelectronic properties controlled by strong confinement in one dimension. In this contribution, we studied interlayer excitons in a vertical p-n junction made of bilayer n-type MoS2 and few layers of p-type GaSe using current sensing atomic force microscopy (CSAFM). The p-n interface is prepared by mechanical exfoliation onto highly ordered pyrolytic graphite (HOPG). Thus the heterostructure creates an ideal layered system with HOPG serving as the bottom contact for the electrical characterization. Home-built Au tips are used as the top contact in CSAFM mode. During the basic diode characterization, the p-n interface shows strong rectification behavior with a rectification ratio of 10(4) at +/- 1 V. The I-V characteristics reveal pronounced photovoltaic effects with a fill factor of 0.55 by an excitation below the band gap. This phenomenon can be explained by the dissociation of interlayer excitons at the interface. The possibility of the interlayer exciton formation is indicated by density functional theory (DFT) calculations on this heterostructure: the valence band of GaSe and the conduction band of MoS2 contribute to an interface-specific state at an energy of about 1.5 eV. The proof of excitonic transitions to that state is provided by photoluminescence measurements at the p-n interface. Finally, photocurrent mapping at the interface under an excitation wavelength of 785 nm provides evidence of efficient extraction of such excitons. Our results demonstrate a pathway towards a 2D device for future optoelectronics and light harvesting assisted by interlayer excitons in a van der Waals (vdW) heterostructure.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据