Van der Waals epitaxial growth and optoelectronics of large-scale WSe2/SnS2 vertical bilayer p\u2013n junctions

Tiefeng Yang,Zhen Wang,Hongjun Liu,Feng Miao,Xuehong Zhang,Biyuan Zheng,Anlian Pan,Litao Sun,Juan Zou,Weida Hu,Tao Xu,Zhaoyang Qi,Yexin Feng,Xiangfeng Duan,Chen Pan

doi:10.1038/s41467-017-02093-z

Abstract

High-quality two-dimensional atomic layered p–n heterostructures are essential for high-performance integrated optoelectronics. The studies to date have been largely limited to exfoliated and restacked flakes, and the controlled growth of such heterostructures remains a significant challenge. Here we report the direct van der Waals epitaxial growth of large-scale WSe2/SnS2 vertical bilayer p–n junctions on SiO2/Si substrates, with the lateral sizes reaching up to millimeter scale. Multi-electrode field-effect transistors have been integrated on a single heterostructure bilayer. Electrical transport measurements indicate that the field-effect transistors of the junction show an ultra-low off-state leakage current of 10−14 A and a highest on–off ratio of up to 107. Optoelectronic characterizations show prominent photoresponse, with a fast response time of 500 μs, faster than all the directly grown vertical 2D heterostructures. The direct growth of high-quality van der Waals junctions marks an important step toward high-performance integrated optoelectronic devices and systems.

Highlights

High-quality two-dimensional atomic layered p–n heterostructures are essential for highperformance integrated optoelectronics
The direct growth of high-quality van der Waals junctions marks an important step toward high-performance integrated optoelectronic device and systems
The results indicate that the bottom uncovered WSe2 monolayer exhibits strong PL emission with a dominant emission peak locating at 766 nm, corresponding to the recombination of excitons[50, 51], whereas the bilayer WSe2/SnS2 region shows apparent PL quenching, with essentially no detectable PL (Fig. 3e)

Summary

Introduction

High-quality two-dimensional atomic layered p–n heterostructures are essential for highperformance integrated optoelectronics. We report the direct van der Waals epitaxial growth of large-scale WSe2/SnS2 vertical bilayer p–n junctions on SiO2/Si substrates, with the lateral sizes reaching up to millimeter scale. Direct vapor growth of large-scale high-quality 2D atomic layered vertical heterostructures, especially p–n junctions, remains a great challenge. We report a two-step vapor phase route to controlled growth of largescale WSe2/SnS2 vertical bilayer p–n junctions on SiO2/Si. The asgrown junctions are highly crystallized, with their lateral sizes reaching up to millimeter scale, representing the largest size of atomic layered vertical heterostructures ever been achieved. Backgate field-effect transistors were fabricated with high on–off ratio, ultra-low leakage current, and show fast photoresponse speed comparing favorably to mechanically staked 2D vertical junctions. The direct growth of high-quality van der Waals junctions marks an important step toward high-performance integrated optoelectronic device and systems

Methods

Results

Conclusion