Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki, Finland.
Phys Rev Lett. 2012 Jul 20;109(3):035503. doi: 10.1103/PhysRevLett.109.035503. Epub 2012 Jul 17.
Using first-principles atomistic simulations, we study the response of atomically thin layers of transition metal dichalcogenides (TMDs)--a new class of two-dimensional inorganic materials with unique electronic properties--to electron irradiation. We calculate displacement threshold energies for atoms in 21 different compounds and estimate the corresponding electron energies required to produce defects. For a representative structure of MoS2, we carry out high-resolution transmission electron microscopy experiments and validate our theoretical predictions via observations of vacancy formation under exposure to an 80 keV electron beam. We further show that TMDs can be doped by filling the vacancies created by the electron beam with impurity atoms. Thereby, our results not only shed light on the radiation response of a system with reduced dimensionality, but also suggest new ways for engineering the electronic structure of TMDs.
利用第一性原理原子模拟方法，我们研究了原子层厚度的过渡金属二卤化物（TMDs）——一类具有独特电子性质的新型二维无机材料——对电子辐照的响应。我们计算了 21 种不同化合物中原子的位移阈能，并估计了产生缺陷所需的相应电子能量。对于 MoS2 的代表性结构，我们进行了高分辨率透射电子显微镜实验，并通过观察在暴露于 80keV 电子束下空位的形成，验证了我们的理论预测。我们进一步表明，TMDs 可以通过用杂质原子填充电子束产生的空位来掺杂。因此，我们的研究结果不仅揭示了具有降低维度的系统的辐射响应，而且为工程化 TMDs 的电子结构提供了新途径。
