欧姆接触
肖特基势垒
半金属
材料科学
单层
凝聚态物理
半导体
费米能级
密度泛函理论
肖特基二极管
纳米技术
带隙
铋
接触电阻
金属半导体结
光电子学
化学
计算化学
物理
图层(电子)
电子
二极管
量子力学
冶金
作者
Tong Su,Yueyan Li,Wei Wang,Weiwei Zhao,Liemao Cao,Yee Sin Ang
标识
DOI:10.1088/1361-6463/acc53f
摘要
Abstract Recent experiment has uncovered semimetal bismuth (Bi) as an excellent electrical contact to monolayer MoS 2 with ultralow contact resistance. The contact physics of the broader semimetal/monolayer-semiconductor family beyond Bi/MoS 2 , however, remains largely unexplored thus far. Here we perform a comprehensive first-principle density functional theory investigation on the electrical contact properties between six archetypal two-dimensional (2D) transition metal dichalcogenide (TMDC) semiconductors, i.e. MoS 2 , WS 2 , MoSe 2 , WSe 2 , MoTe 2 and WTe 2 , and two representative types of semimetals, Bi and antimony (Sb). As Bi and Sb work functions energetically aligns well with the TMDC conduction band edge, Ohmic or nearly-Ohmic n -type contacts are prevalent. The interlayer distance of semimetal/TMDC contacts are significantly larger than that of the metal/TMDC counterparts, which results in only weak metalization of TMDC upon contact formation. Intriguingly, such weak metalization generates semimetal-induced gap states (SMIGSs) that extends below the conduction band minimum, thus offering an effective mechanism to reduce or eliminate the n -type Schottky barrier height (SBH) while still preserving the electronic structures of 2D TMDC. A modified Schottky–Mott rule that takes into account SMIGS, interface dipole potential, and Fermi level shifting is proposed, which provides an improved agreement with the density functional theory-simulated SBH. We further show that the tunneling-specific resistivity of Sb/TMDC contacts are generally lower than the Bi counterparts, thus indicating a better charge injection efficiency can be achieved through Sb contacts. Our findings reveal the promising potential of Bi and Sb as excellent companion electrode materials for advancing 2D semiconductor device technology.
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