Browsing by Author "Chen, Chi"

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Large-Area and Strain-Reduced Two-Dimensional Molybdenum Disulfide Monolayer Emitters on a Three-Dimensional Substrate
(2019-07-24)
Chang, Chiao-Yun
;
Lin, Hsiang-Ting
;
Lai, Ming-Sheng
;
Yu, Cheng-Li
;
Wu, Chong-Rong
Atomically thin membranes of two-dimensional (2-D) transition-metal dichalcogenides (TMDCs) have distinct emission properties, which can be utilized for realizing ultrathin optoelectronic integrated systems in the future. Growing a large-area and strain-reduced monolayer 2-D material on a three-dimensional (3-D) substrate with microstructures or nanostructures is a crucial technique because the electronic band structure of TMDC atomic layers is strongly affected by the number of stacked layers and strain. In this study, a large-area and strain-reduced MoS2 monolayer was fabricated on a 3D substrate through a two-step growth procedure. The material characteristics and optical properties of monolayer TMDCs fabricated on the nonplanar substrate were examined. The growth of monolayer MoS2 on a cone-shaped sapphire substrate effectively reduced the tensile strain induced by the substrate by decreasing the thermal expansion mismatch between the 2-D material and the substrate. Monolayer MoS2 grown on the nonplanar substrate exhibited uniform strain reduction and luminescence intensity. The fabrication of monolayer MoS2 on a nonplanar substrate increased the light extraction efficiency. In the future, large-area and strain-reduced 2-D TMDC materials grown on a nonplanar substrate can be employed as novel light-emitting devices for applications in lighting, communication, and displays for the development of ultrathin optoelectronic integrated systems.
Strain-reduced and Photoluminescence Enhanced of MoS2 Emitters on Three-Dimensional Substrate
(2020-01-01)
Lee, Andrew Boyi
;
Chang, Chiao-Yun
;
Lin, Hsiang-Ting
;
Lai, Ming-Sheng
;
Yu, Cheng-Li
Two-dimensional (2D) atomic transition metal dichalcogenides (TMDCs) have distinct emission properties, which can be applied for ultrathin detectors and light-emitters in the future. In this study, strain and photoluminescence of MoS2 monolayer on a 3D substrate through a two-step growth procedure was analyzed. The structural of materials and those optical properties of monolayer TMDCs fabricated on the planar and nonplanar substrate were examined. Monolayer MoS2 grown on the nonplanar substrate exhibited uniform strain reduction and luminescence intensity. The fabrication of monolayer MoS2 on a nonplanar substrate increased the light extraction efficiency. In the future, strain-reduced 2D TMDC materials grown on a nonplanar substrate can be employed as novel light-emitting devices for applications in light-emitters, communication, and displays for ultrathin optoelectronic integrated systems.
Toward epitaxially grown two-dimensional crystal hetero-structures: Single and double MoS2/graphene hetero-structures by chemical vapor depositions
(2014-08-18)
Lin, Meng-Yu
;
Chang, Chung-En
;
Wang, Cheng-Hung
;
Su, Chen-Fung
;
Chen, Chi
Uniform large-size MoS2/graphene hetero-structures fabricated directly on sapphire substrates are demonstrated with layer-number controllability by chemical vapor deposition (CVD). The cross-sectional high-resolution transmission electron microscopy (HRTEM) images provide the direct evidences of layer numbers of MoS2/graphene hetero-structures. Photo-excited electron induced Fermi level shift of the graphene channel are observed on the single MoS2/graphene hetero-structure transistors. Furthermore, double hetero-structures of graphene/MoS2/graphene are achieved by CVD fabrication of graphene layers on top of the MoS2, as confirmed by the cross-sectional HRTEM. These results have paved the possibility of epitaxially grown multi-hetero-structures for practical applications. (C) 2014 AIP Publishing LLC.