Han Yeongseo, Chae Minji, Choi Dahyun, Song Inseon, Ko Changhyun, Cresti Alessandro, Theodorou Christoforos, Joo Min-Kyu
Department of Applied Physics, Sookmyung Women's University, Seoul 04310, Republic of Korea.
Institute of Advanced Materials and Systems, Sookmyung Women's University, Seoul 04310, Republic of Korea.
ACS Appl Mater Interfaces. 2023 Dec 20;15(50):58605-58612. doi: 10.1021/acsami.3c13699. Epub 2023 Dec 5.
The inherent interlayer resistance in two-dimensional (2D) van der Waals (vdW) multilayers is expected to significantly influence the carrier density profile along the thickness, provoking spatial modification and separation of the conducting channel inside the multilayers, in conjunction with the thickness-dependent carrier mobility. However, the effect of the interlayer resistance on the variation in the carrier density profile and its direction along the thickness under different electrostatic bias conditions has been elusive. Here, we reveal the presence of a negative differential interlayer resistance (NDIR) in WSe multilayers by considering various contact electrode configurations: (i) bottom contact, (ii) top contact, and (iii) vertical double-side contact (VDC). The contact-structure-dependent shape modification of the transconductance clearly manifests the redistribution of carrier density and indicates the direction of the conducting channel migration along the thickness. Furthermore, the distinct characteristic of the electrically tunable NDIR in 2D WSe multilayers is revealed by the observed discrepancy between the top- and bottom-channel resistances determined by four-probe measurements with VDC. Our results provide an optimized device layout and further insights into the distinct carrier transport mechanism in 2D vdW multilayers.
二维（2D）范德华（vdW）多层膜中的固有层间电阻预计会显著影响沿厚度方向的载流子密度分布，引发多层膜内部导电通道的空间改变和分离，同时伴随着与厚度相关的载流子迁移率。然而，在不同静电偏置条件下，层间电阻对载流子密度分布变化及其沿厚度方向的影响一直难以捉摸。在此，我们通过考虑各种接触电极配置揭示了WSe多层膜中负微分层间电阻（NDIR）的存在：（i）底部接触，（ii）顶部接触，以及（iii）垂直双侧接触（VDC）。跨导的接触结构依赖性形状改变清楚地表明了载流子密度的重新分布，并指示了导电通道沿厚度方向的迁移方向。此外，通过VDC四探针测量确定的顶部和底部通道电阻之间观察到的差异，揭示了二维WSe多层膜中电可调NDIR的独特特性。我们的结果提供了优化的器件布局，并进一步深入了解二维vdW多层膜中独特的载流子传输机制。
