Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States.
ACS Nano. 2014 Mar 25;8(3):2880-8. doi: 10.1021/nn500044q. Epub 2014 Feb 6.
Achieving low resistance contacts is vital for the realization of nanoelectronic devices based on transition metal dichalcogenides. We find that intrinsic defects in MoS2 dominate the metal/MoS2 contact resistance and provide a low Schottky barrier independent of metal contact work function. Furthermore, we show that MoS2 can exhibit both n-type and p-type conduction at different points on a same sample. We identify these regions independently by complementary characterization techniques and show how the Fermi level can shift by 1 eV over tens of nanometers in spatial resolution. We find that these variations in doping are defect-chemistry-related and are independent of contact metal. This raises questions on previous reports of metal-induced doping of MoS2 since the same metal in contact with MoS2 can exhibit both n- and p-type behavior. These results may provide a potential route for achieving low electron and hole Schottky barrier contacts with a single metal deposition.
实现低电阻接触对于基于过渡金属二硫属化物的纳米电子器件的实现至关重要。我们发现 MoS2 中的本征缺陷主导着金属/MoS2 接触电阻，并提供了一个与金属接触功函数无关的低肖特基势垒。此外，我们还表明，MoS2 在同一样品的不同点可以表现出 n 型和 p 型传导。我们通过互补的表征技术独立地识别出这些区域，并展示了费米能级如何在数十纳米的空间分辨率内移动 1 eV。我们发现这些掺杂的变化与缺陷化学有关，与接触金属无关。这对以前关于 MoS2 金属诱导掺杂的报道提出了质疑，因为与 MoS2 接触的相同金属可以表现出 n 型和 p 型行为。这些结果可能为通过单一金属沉积实现低电子和空穴肖特基势垒接触提供了一种潜在途径。
