Chinese scholar to achieve two-dimensional atomic crystal two-layer vertical pn junction large area controllable preparation

Set micro-mesh news, according to Hunan University report, in recent years, two-dimensional layered semiconductor due to its novel physical and structural properties, has shown great potential for the next generation of electronic and optoelectronic integrated system.Compared to a simple two Heterojunction of Dimensional Materials and 2D Layered Materials Due to the steep interface with atomic layer thickness and the tunable band arrangement, it is more suitable for multi-functional on-chip integration and attracts much attention. However, the existing research Most of them stay in the use of mechanical stripping and stacking method to get the vertical heterojunction, and this method due to the obtained heterojunction shape and size can not be controlled, greatly limiting its future application development.In comparison, by direct However, the direct growth of large-sized, high-quality two-dimensional atomic-layered vertical heteroj unction, especially pn heterogeneity Results are still a big problem for the scientific community.

Recently, the cross-research team of nano-photonic materials and devices led by Professor Pan An-lian, a professor at the Institute of Micro and Nano Information Devices and Systems, Hunan University, for the first time realized the vertical double-walled pn heterojunction WSe2 / SnS2 with macroscopic millimeter size using controlled chemical vapor deposition And achieves the application in high performance integrated optoelectronic devices.This achievement is an important breakthrough in the field of novel two-dimensional atomic crystal photovoltaic research and is described in the article "Van der Waals epitaxial growth and optoelectronics of large-scale WSe2 / SnS2vertical bilayer p-n junctions' was published in the top international journal Nature Communications (IF = 12.124). The lead author of the paper is PhD students Yang Tiefeng and Zheng Biluan who are guided by Prof. Pan Anli.

In this work, the researchers achieved a fine large-area monolayer-monolayer controlled growth based on a profound understanding of the growth process by adopting the advanced two-step thermal chemical vapor deposition method and obtained the largest WSe2 / SnS2 vertical single crystal double pn heterojunction fabrication, the lateral size of the heterojunction has reached the order of millimeters.In this large area of ​​two-dimensional pn heterojunction, researchers also designed and constructed three different types of devices , Parallel-series mode heterojunction devices have been shown to exhibit very low leakage currents (~ 10-14A) as well as high transistor switching ratios (107) by characterization, with good optoelectronic response characteristics, many The performance is better than the previously reported index.The response time to 520nm laser is about 500 microseconds, exceeding all the directly growing vertical pn heterojunction reported, even better than most of the heterojunction formed by mechanical peel transfer.In addition Through the realization of three different performance devices on the same large-size two-dimensional heterojunction, the corresponding devices can be selected according to the specific use requirements in the future and achieve a certain sense of integration. The next step will be to build new two-dimensional material integrated optoelectronic devices and systems to lay the foundation.

The research work was supported by such topics as National Outstanding Youth Fund, National Natural Science Foundation of China and Hunan Provincial Science and Technology Plan Key Project and was supported by the team of Hu Weida, Shanghai Institute of Technical Physics, Miao Feng Team of Nanjing University and Sun Litao of Southeast University.