二維過渡金屬二硫屬化物為極具潛力的新穎材料，尤其是不同材料或堆疊方式組成的異質結構，除了具有二維材料尺度上的優勢，其能帶結構的可調控性，有助於應用於半導體及光電元件中。
本研究利用第一原理計算探討單層二硫化鉬、二硫化鎢及其組成之異質結構的導電行為，討論內容包含利用能帶結構、態密度及穿隧圖譜分析單層二硫化鉬及二硫化鎢能隙大小、導帶及價帶主導軌域與載子傳輸異向性；垂直式異質結構則利用實空間態密度，分析AB1、AA1及AA3三種堆疊方式及20%~100%的覆蓋面積比例之間的變化關係對於層間耦合的影響，並且解釋載子傳輸行為；水平式異質結構則依據介面的不同，分析載子於扶手型及鋸齒型方向上傳輸的差異。
我們的研究結果顯示，單層二硫化鉬及單層二硫化鎢為直接能隙半導體，垂直異質結構以AB1及AA1堆疊方式最為穩定，並且在AA1-100%的堆疊下，載子傳輸係數最高，水平異質結構則是以鋸齒型方向的傳輸性質較好，意味著異質結構可以藉由堆疊方式、覆蓋面積比例及傳輸方向來調控載子的傳輸行為，增加應用上的多元性。

Two-dimensional transition metal dichalcogenides (TMDs) are one of the most promising material, especially in their heterostructure forms. The advantages of 2D TMDs not only come from their low dimensional structures but also the controllable electronic properties which are with fully potential in semiconductor or photoelectric applications.
We carry out first principles calculations to study conducting behavior of monolayer MoS2, WS2 and their heterostructures. The band structures, DOS and transmission spectra are used to analyze the electric properties of monolayer MoS2 and WS2. In the vertical heterostructures case, we discuss the relation between LDOS and transmission spectra under different stacking types and coverage ratio from 20% to 100%. In addition to vertical heterostructures, the carrier transmission along armchair or zigzag direction is calculated in lateral heterostructures.
Our results reveal that both monolayer MoS2 and WS2 are direct bandgap semiconductors. The AB1 and AA1 stacking types are more stable than AA3 in the vertical heterostructures and the AA1-100% has the highest transmission coefficient. The carrier shows better transmission along zigzag direction than armchair in the lateral heterostructures. Based on our calculations, we shows that their electronic properties depend on stacking types, coverage ratios or the transmission direction, which have multiple applications.

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