Najmaei Sina, Neupane Mahesh R, Nichols Barbara M, Burke Robert A, Mazzoni Alexander L, Chin Matthew L, Rhodes Daniel A, Balicas Luis, Franklin Aaron D, Dubey Madan
Sensors and Electron Devices Directorate, United States Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD, 20783, USA.
General Technical Services, LLC, 1451 Route 34 South-Suite 301, Wall Township, NJ, 07727, USA.
Small. 2018 May;14(20):e1703808. doi: 10.1002/smll.201703808. Epub 2018 Apr 16.
The mechanisms of carrier transport in the cross-plane crystal orientation of transition metal dichalcogenides are examined. The study of in-plane electronic properties of these van der Waals compounds has been the main research focus in recent years. However, the distinctive physical anisotropies, short-channel physics, and tunability of cross layer interactions can make the study of their electronic properties along the out-of-plane crystal orientation valuable. Here, the out-of-plane carrier transport mechanisms in niobium diselenide and hafnium disulfide are explored as two broadly different representative materials. Temperature-dependent current-voltage measurements are preformed to examine the mechanisms involved. First principles simulations and a tunneling model are used to understand these results and quantify the barrier height and hopping distance properties. Using Raman spectroscopy, the thermal response of the chemical bonds is directly explored and the insight into the van der Waals gap properties is acquired. These results indicate that the distinct cross-plane carrier transport characteristics of the two materials are a result of material thermal properties and thermally mediated transport of carriers through the van der Waals gaps. Exploring the cross-plane electron transport, the exciting physics involved is unraveled and potential new avenues for the electronic applications of van der Waals layers are inspired.
研究了过渡金属二硫属化物在垂直于平面晶体取向中的载流子传输机制。近年来，对这些范德华化合物的面内电子性质的研究一直是主要研究重点。然而，其独特的物理各向异性、短沟道物理特性以及跨层相互作用的可调性，使得研究它们沿垂直于平面晶体取向的电子性质具有重要价值。在此，将二硒化铌和二硫化铪作为两种具有广泛差异的代表性材料，探索其垂直于平面的载流子传输机制。进行了与温度相关的电流-电压测量，以研究其中涉及的机制。使用第一性原理模拟和隧穿模型来理解这些结果，并量化势垒高度和跳跃距离特性。利用拉曼光谱直接探究化学键的热响应，并获得对范德华间隙特性的深入了解。这些结果表明，这两种材料独特的垂直于平面的载流子传输特性是材料热性质以及载流子通过范德华间隙的热介导传输的结果。通过探索垂直于平面的电子传输，揭示了其中令人兴奋的物理现象，并为范德华层的电子应用激发了潜在的新途径。
