Epitaxial growth of two-dimensional layered transition-metal dichalcogenides and their optoelectronic applications

Time 2018-11-08 10:25~10:50 Place Rm. 600A
Code No. DP-O06 Session Chair
Name Prof. Yumeng Shi
Affiliation Shenzhen University
Title Epitaxial growth of two-dimensional layered transition-metal dichalcogenides and their optoelectronic applications
Contents
Recently there have been many research breakthroughs in two dimensional (2D) materials including graphene, boron nitride (h-BN), black phosphors (BP) and transition metal dichalcogenides (TMDCs), and 2D perovskites. The unique electrical, optical, and thermal properties in 2D materials are associated with their strictly defined low dimensionalities. These materials provide a wide range of basic building blocks for next generation electronics. The chemical vapor deposition (CVD) technique has shown great promise to generate high-quality TMDC layers with scalable size, controllable thickness and excellent electronic properties suitable for both technological applications and fundamental sciences. The capability to precisely engineer 2D materials by chemical approaches has also given rise to fascinate new physics which could lead to exciting new applications. We introduce the latest development of TMDC synthesis by CVD approaches and provide further insight for the controllable and reliable synthesis of atomically thin TMDCs. Understanding on the vapor phase growth mechanism of 2D TMDCs could benefit the formation of complicated heterostructures and novel artificial 2D lattices for advanced optoelectronic applications. CVD shows great promise to generate TMDCs layers including WS2 monolayers with scalable size, controllable thickness, and excellent electronic properties. Intricate defects such as vacancies, point defects and grain boundaries are usually inevitably generated during the CVD growth process. These structural imperfections can act as efficient traps for charges and strongly influence optical properties of the host materials. Control of the charge populations is an effective method to modulate the optical properties of TMDCs monolayers. It is worthwhile to further explore the formation of trions and biexcitons in WS2 monolayers by chemical doping and discover an effective way to control their contributions to PL emission. Meanwhile, we further show that photodetectors based on the composites of transition metal dichalcogenides (TMDCs) and perovskites exhibit performances superior to those of pure perovskite photodetectors. This is mainly due to the high charge mobility of TMDCs and the improved interfacial charge transfer in the hybrid structure. Our recent results should aid in the design and understanding of optoelectronic devices based on quantum confined atomically thin 2D materials systems.