Department of Electrical and Computer Engineering, University of California, Santa Barbara, California, 93106, USA.
Department of Materials Science and Nanoengineering, Rice University, Houston, Texas, 77005, USA.
Sci Rep. 2017 Aug 30;7(1):9965. doi: 10.1038/s41598-017-08776-3.
Ordered arrays of quantum dots in two-dimensional (2D) materials would make promising optical materials, but their assembly could prove challenging. Here we demonstrate a scalable, site and size controlled fabrication of quantum dots in monolayer molybdenum disulfide (MoS), and quantum dot arrays with nanometer-scale spatial density by focused electron beam irradiation induced local 2H to 1T phase change in MoS. By designing the quantum dots in a 2D superlattice, we show that new energy bands form where the new band gap can be controlled by the size and pitch of the quantum dots in the superlattice. The band gap can be tuned from 1.81 eV to 1.42 eV without loss of its photoluminescence performance, which provides new directions for fabricating lasers with designed wavelengths. Our work constitutes a photoresist-free, top-down method to create large-area quantum dot arrays with nanometer-scale spatial density that allow the quantum dots to interfere with each other and create artificial crystals. This technique opens up new pathways for fabricating light emitting devices with 2D materials at desired wavelengths. This demonstration can also enable the assembly of large scale quantum information systems and open up new avenues for the design of artificial 2D materials.
二维（2D）材料中有序排列的量子点将成为有前途的光学材料，但它们的组装可能具有挑战性。在这里，我们通过聚焦电子束辐照诱导 MoS 中的局部 2H 到 1T 相转变，展示了在单层二硫化钼（MoS）中以及具有纳米级空间密度的量子点阵列中进行可扩展、位置和尺寸可控的量子点制造。通过在 2D 超晶格中设计量子点，我们表明在新能带中形成了新的能带间隙，其可以通过超晶格中量子点的尺寸和间距来控制。带隙可以从 1.81eV 调谐到 1.42eV，而不会损失其光致发光性能，这为制造具有设计波长的激光器提供了新的方向。我们的工作构成了一种无需光刻胶的自上而下的方法，可制造具有纳米级空间密度的大面积量子点阵列，使量子点能够相互干涉并形成人造晶体。这项技术为在所需波长下制造二维材料发光器件开辟了新途径。这种演示还可以实现大规模量子信息系统的组装，并为人工二维材料的设计开辟新途径。
