Kang Seohui, Eshete Yonas Assefa, Lee Sujin, Won Dongyeun, Im Saemi, Lee Sangheon, Cho Suyeon, Yang Heejun
Department of Chemical Engineering and Materials Science, Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea.
Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
iScience. 2021 Dec 3;25(1):103563. doi: 10.1016/j.isci.2021.103563. eCollection 2022 Jan 21.
Tungsten disulfide (WS) has tunable bandgaps, which are required for diverse optoelectronic device applications. Here, we report the bandgap modulation in WS monolayers with two-dimensional core-shell structures formed by unique growth mode in chemical vapor deposition (CVD). The core-shell structures in our CVD-grown WS monolayers exhibit contrasts in optical images, Raman, and photoluminescence spectroscopy. The strain and doping effects in the WS, introduced by two different growth processes, generate PL peaks at 1.83 eV (at the core domain) and 1.98 eV (at the shell domain), which is distinct from conventional WS with a primary PL peak at 2.02 eV. Our density functional theory (DFT) calculations explain the modulation of the optical bandgap in our core-shell-structured WS monolayers by the strain, accompanying a direct-to-indirect bandgap transition. Thus, the core-shell-structured WS monolayers provide a practical method to fabricate lateral heterostructures with different optical bandgaps, which are required for optoelectronic applications.
二硫化钨（WS）具有可调节的带隙，这是各种光电器件应用所必需的。在此，我们报道了通过化学气相沉积（CVD）中独特的生长模式形成的具有二维核壳结构的WS单层中的带隙调制。我们通过CVD生长的WS单层中的核壳结构在光学图像、拉曼光谱和光致发光光谱中表现出差异。由两种不同生长过程引入的WS中的应变和掺杂效应在1.83 eV（在核域）和1.98 eV（在壳域）处产生PL峰，这与具有2.02 eV的主要PL峰的传统WS不同。我们的密度泛函理论（DFT）计算解释了应变在我们的核壳结构WS单层中对光学带隙的调制，伴随着直接到间接带隙的转变。因此，核壳结构的WS单层提供了一种制造具有不同光学带隙的横向异质结构的实用方法，这是光电器件应用所必需的。
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