1T phase as an efficient hole injection layer to TMDs transistors: a universal approach to achieve p-type contacts
1T phase as an efficient hole injection layer to TMDs transistors: a universal approach to achieve p-type contacts
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1T 相作为 TMD 晶体管的高效空穴注入层：实现 p 型接触的通用方法
DOI：
10.1088/2053-1583/aac859
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发表时间：
2018
期刊：
影响因子：
5.5
通讯作者：
Chen Zhongfang
中科院分区：
文献类型：
--
作者：
Hu Xiaohui;Wang Yifeng;Shen Xiaodong;Krasheninnikov Arkady V;Sun Litao;Chen Zhongfang
最近，与具有直接沉积在2 H-MoS 2上的金属的那些相比，具有1 T-MoS 2电极的所制造的MoS 2场效应晶体管（FET）表现出具有相当低的接触电阻的优异性能（Kappera等人，2014 Nat.Mater. #20112;，但其原因仍不明确。通过密度泛函理论计算，研究了1 T/2 H MoS 2界面的载流子注入，发现虽然1 T/2 H MoS 2界面的肖特基势垒高度（SBH）值可以通过控制堆叠方式来调节，但不同堆叠方式的1 T/2 H MoS 2界面的p型SBH值均低于相应的n型SBH值，这表明金属1 T相可以用作2 H-MoS 2的有效空穴注入层。此外，与n型Au/MoS 2和Pd/MoS 2接触相比，1 T/2 H-MoS 2界面的p型SBH值要低得多，这是由于1 T-MoS 2和2 H-MoS 2之间的有效空穴注入。这可以解释具有1 T-MoS 2电极的MoS 2 FET中的低接触电阻。值得注意的是，SBH值可以通过外部电场有效地调制，并且在适当的电场下可以实现显著低的p型SBH值。我们还证明，这种方法也是有效的WS 2，WSe 2和MoSe 2系统，这表明该方法可以最有可能扩展到其他TMD，从而可能打开新的有前途的途径接触工程在这些材料。
Recently, the fabricated MoS2 field effect transistors (FETs) with 1T-MoS2 electrodes exhibit excellent performance with rather low contact resistance, as compared with those with metals deposited directly on 2H-MoS2 (Kappera et al 2014 Nat. Mater. 13 1128), but the reason for that remains elusive. By means of density functional theory calculations, we investigated the carrier injection at the 1T/2H MoS2 interface and found that although the Schottky barrier height (SBH) values of 1T/2H MoS2 interfaces can be tuned by controlling the stacking patterns, the p-type SBH values of 1T/2H MoS2 interfaces with different stackings are lower than their corresponding n-type SBH values, which demonstrated that the metallic 1T phase can be used as an efficient hole injection layer for 2H-MoS2. In addition, as compared to the n-type Au/MoS2 and Pd/MoS2 contacts, the p-type SBH values of 1T/2H MoS2 interfaces are much lower, which stem from the efficient hole injection between 1T-MoS2 and 2H-MoS2. This can explain the low contact resistance in the MoS2 FETs with 1T-MoS2 electrodes. Notably, the SBH values can be effectively modulated by an external electric field, and a significantly low p-type SBH value can be achieved under an appropriate electric field. We also demonstrated that this approach is also valid for WS2, WSe2 and MoSe2 systems, which indicates that the method can most likely be extended to other TMDs, and thus may open new promising avenues of contact engineering in these materials.