摘要
The fabrication of heterostructures of two-dimensional semiconductors with specific bandgaps is an important approach to realizing the full potential of these materials in electronic and optoelectronic devices. Several groups have recently reported the direct growth of lateral and vertical heterostructures based on monolayers of typical semiconducting transition metal dichalcogenides （TMDCs） such as WSe2, MoSe2, WS2, and MoS2. Here, we demonstrate the single-step direct growth of lateral and vertical heterostructures based on bandgap-tunable Mo1-xWxS2 alloy monolayers by the sulfurization of patterned thin films of WO3 and MoO3. These patterned films are capable of generating a wide variety of concentration gradients by the diffusion of transition metals during the crystal growth phase. Under high temperatures, this leads to the formation of monolayer crystals of Mo1-xWxS2 alloys with various compositions and bandgaps, depending on the positions of the crystals on the substrates. Heterostructures of these alloys are obtained through stepwise changes in the ratio of W/Mo within a single domain during low-temperature growth. The stabilization of the monolayer Mo1-xWxS2 alloys, which often degrade even under gentle conditions, was accomplished by coating the alloys with other monolayers. The present findings demonstrate an efficient means of both studying and optimizing the optical and electrical properties of TMDC-based heterostructures to allow use of the materials in future device applications.
有特定的 bandgaps 的二维的半导体的 heterostructures 的制造是认识到这些材料的完整的潜力在的一条重要途径电子并且 optoelectronic 设备。几个组最近基于象 WSe <sub>2</sub>, MoSe <sub>2</sub>, WS <sub>2</sub>, 和瞬间 <sub>2</sub> 那样的典型半导体的转变金属 dichalcogenides (TMDC ) 的单层报导了侧面、垂直的 heterostructures 的直接生长。这里，我们基于 bandgap 悦耳的瞬间 <sub>1-x</sub 表明侧面、垂直的 heterostructures 的单个步的直接生长 > W <sub> x </sub > 由 WO <sub>3</sub> 和哞 <sub>3</sub> 的有图案的薄电影的 sulfurization 的 S <sub>2</sub> 合金单层。这些有图案的电影能够在水晶生长阶段期间由转变金属的散开产生许多集中坡度。在高温度下面，这导致瞬间 <sub>1-x</sub 的单层晶体的形成 > W <sub> x </sub > 有各种各样的作文和 bandgaps 的 S <sub>2</sub> 合金，在底层上取决于晶体的位置。这些合金的 Heterostructures 在低温度的生长期间在一个单个领域以内在 W/Mo 的比率通过逐步的变化被获得。单层瞬间 <sub>1-x</sub 的稳定 > W <sub> x </sub > S <sub>2</sub> 合金，经常甚至在轻轻的条件下面降级，被涂层完成有另外的单层的合金。现在的调查结果表明学习并且优化基于 TMDC 的 heterostructures 的光、电的性质在未来设备应用允许材料的使用的一个有效工具。
