Electronic excitation-induced semiconductor-to-metal transition in monolayer MoTe2
Electronic excitation-induced semiconductor-to-metal transition in monolayer MoTe2
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DOI：
10.1103/physrevb.94.094114
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发表时间：
2016-09-29
影响因子：
3.7
通讯作者：
Tominaga, J.
中科院分区：
文献类型：
--
作者：
Kolobov, A. V.;Fons, P.;Tominaga, J.
过渡金属二硫属化合物（TMDC）单层膜的可逆多晶性是近年来学术界和应用领域的研究热点。特别感兴趣的是MoTe 2，其中稳定的半导体2H和亚稳（半）金属1T '相具有相当小的能量差，这意味着这种转变的低能量成本。在这项工作中，使用第一性原理计算，我们证明，存在一个以前未知的阶段MoTe 2，即扭曲的三角棱柱相交替较短和较长的债券和债券的角度，这是形成在电子激发态由于人口反转。该相是不稳定的，并且在激发停止后衰减到基态2H状态，是金属的，并且可以起到降低通向亚稳1T '相的能量势垒的作用。我们的研究结果表明，存在一个以前未探索的路线，超快的本地和选择性的能带结构控制在单层TMDC使用电子激发，这将显着拓宽这些材料的应用范围。
Reversible polymorphism of monolayer transition-metal dichalcogenides (TMDC) has currently attracted much attention from both academic and applied perspectives. Of special interest is MoTe2, where the stable semiconducting 2H and metastable (semi) metallic 1T' phases have a rather small energy difference implying the low-energy cost of such a transition. In this work, using first-principles calculations, we demonstrate that there exists a previously unknown phase of MoTe2, namely a distorted trigonal prismatic phase with alternating shorter and longer bonds and bond angles, that is formed in the electronically excited state due to population inversion. This phase, which is unstable and decays to the ground 2H state after cessation of the excitation, is metallic and can act to lower the energy barrier on the way to the metastable 1T' phase. Our findings indicate that there exists a previously unexplored route of ultrafast local and selective band-structure control in monolayer TMDC using electronic excitation, which will significantly broaden the application spectrum of these materials.