Step-Edge-Guided Nucleation and Growth of Aligned WSe₂ on Sapphire via a Layer-over-Layer Growth Mode

Citations Over TimeTop 10% of 2015 papers

Abstract

Two-dimensional (2D) materials beyond graphene have drawn a lot of attention recently. Among the large family of 2D materials, transitional metal dichalcogenides (TMDCs), for example, molybdenum disulfides (MoS2) and tungsten diselenides (WSe2), have been demonstrated to be good candidates for advanced electronics, optoelectronics, and other applications. Growth of large single-crystalline domains and continuous films of monolayer TMDCs has been achieved recently. Usually, these TMDC flakes nucleate randomly on substrates, and their orientation cannot be controlled. Nucleation control and orientation control are important steps in 2D material growth, because randomly nucleated and orientated flakes will form grain boundaries when adjacent flakes merge together, and the formation of grain boundaries may degrade mechanical and electrical properties of as-grown materials. The use of single crystalline substrates enables the alignment of as-grown TMDC flakes via a substrate-flake epitaxial interaction, as demonstrated recently. Here we report a step-edge-guided nucleation and growth approach for the aligned growth of 2D WSe2 by a chemical vapor deposition method using C-plane sapphire as substrates. We found that at temperatures above 950 °C the growth is strongly guided by the atomic steps on the sapphire surface, which leads to the aligned growth of WSe2 along the step edges on the sapphire substrate. In addition, such atomic steps facilitate a layer-over-layer overlapping process to form few-layer WSe2 structures, which is different from the classical layer-by-layer mode for thin-film growth. This work introduces an efficient way to achieve oriented growth of 2D WSe2 and adds fresh knowledge on the growth mechanism of WSe2 and potentially other 2D materials.

Related Papers

• → Controlled synthesis of high-quality crystals of monolayer MoS2 for nanoelectronic device application(2016)58 cited
• → A new (2 × 1) dimerized structure of monolayer 1T-molybdenum disulfide, studied from first principles calculations(2013)93 cited
• → A controllable synthesis of uniform MoS 2 monolayers on annealed molybdenum foils(2017)9 cited
• → Structural, electronic and adsorption properties of monolayer 2H-MoS2 on graphene substrates: A computational study(2019)11 cited
• → Surface Modification of Monolayer MoS2 by Baking for Biomedical Applications(2020)7 cited