16:30 〜 16:45
▼ [15p-2U-11] Vertical Heterostructures of MoS2 and Graphene Nanoribbons by Two-Step Chemical Vapor Deposition for High-Gain Photodetectors
キーワード：Graphene nanoribbons,MoS2,heterostructures
Heterostructures of 2D layered materials have attracted great interest due to their electronic and optical properties, which are expected by combining different types of 2D materials [1]. On the other hand, reduction of the dimensionality from 2D to 1D, such as graphene nanoribbons (GNRs), is also interesting due to the electron confinement and unique edge effects [2]. Here, we demonstrate bottom-up growth of MoS2/GNR heterostructures by a two-step chemical vapor deposition (CVD) method [3]. It is a unique growth process because 2D materials of MoS2 could grow in 1D direction by following the 1D nature of our GNRs.
The GNRs were first grown by ambient pressure CVD on an epitaxial Cu(100) film as reported previously [4]. After transferring on SiO2, the GNRs were subjected to the second CVD to grow MoS2 using MoO3 and S powder as feedstock. The MoS2 layer was found to grow preferentially on the surface of the GNRs, while the coverage could be further tuned by adjusting the growth conditions. Figure 1a,b shows the SEM images after the second CVD with a substrate temperature of 900 ºC for 30 min, where the dark contrast corresponds to the MoS2 grown on the GNR. Raman spectra confirmed a single-layer MoS2 grown on GNR, while from the comparison with the single-layer MoS2 domains grown on sapphire, we found that the PL quenching effect by GNRs. Furthermore, the transport properties under light illumination were measured, as illustrated in Figure 1c, and high photoinduced current modulation for the heterostructures were observed upon illumination with visible light (Figure 1d) [4]. This optical response is higher than that of the heterostructure of MoS2/graphene sheet [5]. The ability to grow a novel 1D heterostructure of layered materials by bottom-up CVD approach will open a new avenue to expand the dimensionality of the material synthesis and applications.
References: [1] H. Lim et al., Chem. Mater. 26 (2014) 4891. [2] X. Li et al., Science 319 (2008) 1229. [3] R. Mohamad Yunus et al., submitted. [4] R. Mohamad Yunus et al., Chem. Mater. 26 (2014) 5215. [5] H. Ago et al., ACS Appl. Mater. Interfaces 7 (2015) 5265.
The GNRs were first grown by ambient pressure CVD on an epitaxial Cu(100) film as reported previously [4]. After transferring on SiO2, the GNRs were subjected to the second CVD to grow MoS2 using MoO3 and S powder as feedstock. The MoS2 layer was found to grow preferentially on the surface of the GNRs, while the coverage could be further tuned by adjusting the growth conditions. Figure 1a,b shows the SEM images after the second CVD with a substrate temperature of 900 ºC for 30 min, where the dark contrast corresponds to the MoS2 grown on the GNR. Raman spectra confirmed a single-layer MoS2 grown on GNR, while from the comparison with the single-layer MoS2 domains grown on sapphire, we found that the PL quenching effect by GNRs. Furthermore, the transport properties under light illumination were measured, as illustrated in Figure 1c, and high photoinduced current modulation for the heterostructures were observed upon illumination with visible light (Figure 1d) [4]. This optical response is higher than that of the heterostructure of MoS2/graphene sheet [5]. The ability to grow a novel 1D heterostructure of layered materials by bottom-up CVD approach will open a new avenue to expand the dimensionality of the material synthesis and applications.
References: [1] H. Lim et al., Chem. Mater. 26 (2014) 4891. [2] X. Li et al., Science 319 (2008) 1229. [3] R. Mohamad Yunus et al., submitted. [4] R. Mohamad Yunus et al., Chem. Mater. 26 (2014) 5215. [5] H. Ago et al., ACS Appl. Mater. Interfaces 7 (2015) 5265.