Qin Ziyu, Loh Leyi, Wang Junyong, Xu Xiaomin, Zhang Qi, Haas Benedikt, Alvarez Carlos, Okuno Hanako, Yong Justin Zhou, Schultz Thorsten, Koch Norbert, Dan Jiadong, Pennycook Stephen J, Zeng Dawen, Bosman Michel, Eda Goki
State Key Laboratory of Materials Processing and Die Mould Technology , Huazhong University of Science and Technology (HUST) , No. 1037, Luoyu Road , Wuhan 430074 , China.
Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551 , Singapore.
ACS Nano. 2019 Sep 24;13(9):10768-10775. doi: 10.1021/acsnano.9b05574. Epub 2019 Sep 13.
Controlled substitutional doping of two-dimensional transition-metal dichalcogenides (TMDs) is of fundamental importance for their applications in electronics and optoelectronics. However, achieving -type conductivity in MoS and WS is challenging because of their natural tendency to form -type vacancy defects. Here, we report versatile growth of -type monolayer WS by liquid-phase mixing of a host tungsten source and niobium dopant. We show that crystallites of WS with different concentrations of substitutionally doped Nb up to 10 cm can be grown by reacting solution-deposited precursor film with sulfur vapor at 850 °C, reflecting the good miscibility of the precursors in the liquid phase. Atomic-resolution characterization with aberration-corrected scanning transmission electron microscopy reveals that the Nb concentration along the outer edge region of the flakes increases consistently with the molar concentration of Nb in the precursor solution. We further demonstrate that ambipolar field-effect transistors can be fabricated based on Nb-doped monolayer WS.
二维过渡金属二硫属化物（TMDs）的可控替代掺杂对于其在电子学和光电子学中的应用至关重要。然而，由于MoS和WS天然倾向于形成p型空位缺陷，在其中实现n型导电性具有挑战性。在此，我们报道了通过主体钨源和铌掺杂剂的液相混合实现n型单层WS的通用生长。我们表明，通过在850°C下使溶液沉积的前驱体膜与硫蒸气反应，可以生长出具有不同浓度（高达10 cm）替代掺杂Nb的WS微晶，这反映了前驱体在液相中的良好混溶性。利用像差校正扫描透射电子显微镜进行的原子分辨率表征表明，沿薄片外边缘区域的Nb浓度与前驱体溶液中Nb的摩尔浓度一致增加。我们进一步证明，可以基于Nb掺杂的单层WS制造双极场效应晶体管。
