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keywords: chemical vapor deposition; heterostructure; optoelectronic devices; substitution; transition-metal dichalcogenides; two-dimensional material
Synthesis of Ultrathin Composition Graded Doped Lateral WSe2/WS2 Heterostructures
Z. Li, J. Zheng, Y. Zhang*, C. Zheng, W.-Y. Woon, M.-C. Chuang, H.-C. Tsai, C.-H. Chen, A. Davis, Z.-Q. Xu, J. Lin, H. Zhang, and Q. Bao*

2017/12/26

Lateral transition-metal dichalcogenide and their heterostructures have attracted substantial attention, but there lacks a simple approach to produce large-scaled optoelectronic devices with graded composition. In particular, the incorporation of substitution and doping into heterostructure formation is rarely reported. Here, we demonstrate growth of a composition graded doped lateral WSe2/WS2 heterostructure by ambient pressure chemical vapor deposition in a single heat cycle. Through Raman and photoluminescence spectroscopy, we demonstrate that the monolayer heterostructure exhibits a clear interface between two domains and a graded composition distribution in each domain. The coexistence of two distinct doping modes, i.e., interstitial and substitutional doping, was verified experimentally. A distinct three-stage growth mechanism consisting of nucleation, epitaxial growth, and substitution was proposed. Electrical transport measurements reveal that this lateral heterostructure has representative characteristics of a photodiodes. The optoelectronic device based on the lateral WSe2/WS2 heterostructure shows improved photodetection performance in terms of a reasonable responsivity and a large photoactive area

ACS Appl. Mater. Interfaces 9 , 34204 (2017)