Synthesis of few layered transition metal dichalcogenides by ion implantation

该项目的总体目标是开发一种大规模的技术，用于均匀合成过渡金属二硫属化物（TMDC），具有受控的单元层数量（例如从1到5），使用离子注入，然后在高温下进行适当的退火。基本上将研究两种方法，即i。将硫族元素离子注入到过渡金属的外延薄膜中，以及ii.将硫族元素和金属离子共同注入中性衬底，优选单晶（例如蓝宝石，MgO），随后在650-850 ℃范围内进行退火。该项目选择了两种具有代表性的半导体TMDC：MoS 2和WS 2。我们的初步实验，使用10 nm厚的，小晶粒多晶Mo膜上沉积的氧化硅衬底和离子注入2.5 × 10 e15硫原子/cm 2时，已证明形成的MoS 2的后注入退火时，在密封的石英坩埚中在750 ℃，在1小时。然而，即使发现拉曼信号在1 cm 2样品面积上是均匀的，但二硫化钼层的晶体取向是随机的，因此在项目期间需要单晶金属膜和衬底，以便在退火时诱导TMDC层的外延生长。WP 1由IKS（Institute forNuclear and Radiation Physics，Keden）领导，主要研究基片制备（包括VSM（Laboratory of Solid State Physics and Magnetism，Keden）和IKS的过渡金属外延沉积）和离子注入（IKS）。由FHI（Fritz-Haber-Institut，柏林）领导的WP 2致力于通过在FHI使用X射线光电子能谱（XPS）以及在CNRS（CNRS-Ecole polytechnique，France）使用原位高分辨率透射电子显微镜（HR-TEM）进行原位观察来研究注入后退火。由CNRS领导的WP 3致力于合成TMDC材料的非原位物理表征，使用TRT（Thales Researchand Technology，France）的拉曼光谱和光致发光，FHI的XPS（使用不同的光子能量测量深度分布），CNRS的HR-TEM，VSM的扫描隧道显微镜和光谱（STM和STS）。此外，角分辨光电子能谱（ARPES）将分包给法国SOLEIL同步加速器的ANTARES小组。TRT领导的WP 4对应于TRT和CNRS对TRT制造的场效应晶体管结构的电子（载流子迁移率）和光电特性。由CNRS领导的WP 5致力于项目管理，成果利用以及与石墨烯旗舰（CNRS-TRT）的合作。

The general objective of the project is to develop a large-scale technique for the uniform synthesis of Transition metal dichalcogenides (TMDCs) with a controlled number of unit layers (say from 1 to 5), using ion implantation, followed by an appropriate annealing at high temperature. Essentially 2 approaches will be studied, namely i. the implantation of the chalcogen ion into epitaxial thin films of the transition metals and ii. the coimplantation of both the chalcogen and metal ions into a neutral substrate, preferably monocrystalline (e.g. apphire, MgO), both followed by an annealing sequence in the 650-850 C range. Two representative semiconductor TMDCs have been chosen for the project: MoS2 and WS2. Our preliminary experiments, using 10 nm-thick, small grain polycrystalline Mo films deposited on oxidized Si substrates and ion implanted with 2.5 x 10e15 sulfur atoms per cm2 have demonstrated the formation of MoS2 when the post-implantation annealing was performed in a sealed quartz ampoule at 750 C during 1 hour. However, even though the Raman signal was found uniform over the 1 cm2 sample area , the crystalline orientation of the MoS2 layers was random, so that monocrystalline metal films and substrates will be needed during the project, in order to induce epitaxial growth of the TMDC layers upon annealing.The project is built around 5 workpackages (WPs). WP1 led by IKS (Institute forNuclear and Radiation Physics, Belgien) deals with substrate preparation (including transition metal epitaxial deposition by VSM (Laboratory of Solid State Physics and Magnetism, Belgien) and IKS) and ion implantation (IKS). WP2 led by FHI (Fritz-Haber-Institut, Berlin) is dedicated to the study of post-implantation annealing by in situ observations using x-ray photoelectron spectroscopy (XPS) at FHI as well as in situ high resolution transmission electron microscopy (HR-TEM) at CNRS (CNRS-Ecole polytechnique, France). WP3 led by CNRS is devoted to the ex situ physical characterizations of the synthesized TMDC materials, using Raman spectroscopy and photoluminescence at TRT (Thales Researchand Technology, France), XPS at FHI (with different photon energies to measure depth profiles), HR-TEM at CNRS, scanning tunnelling microscopy and spectroscopy (STM and STS) at VSM. Moreover, angle resolved photoelectron spectroscopy (ARPES) will be subcontracted to the ANTARES group of the SOLEIL synchrotron in France. WP4 led by TRT corresponds to the electronic (carrier mobility) and optoelectronic characterizations by TRT and CNRS of field-effect transistor structures fabricated by TRT. WP5 led by CNRS is dedicated to the project management, the exploitation of the results and the partnership with the Graphene Flagship (CNRS-TRT).