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技术，用于均匀合成具有控制单位层数（例如从1到5）的过渡金属二硫族化合物（TMDCs），使用离子注入，然后在高温下进行适当的退火。主要研究两种方法：一是将硫离子注入过渡金属外延薄膜；二是将硫离子注入过渡金属外延薄膜。将所述硫离子和金属离子共同注入中性衬底，优选单晶（例如，磷灰石、氧化镁），然后在650-850℃范围内进行退火程序。该项目选择了两种具有代表性的半导体TMDCs: MoS2和WS2。我们的初步实验使用10纳米厚的小晶粒Mo薄膜沉积在氧化的Si衬底上，并以每cm2 2.5 x 10e15个硫原子注入离子，结果表明，在750℃的密封石英安瓿中，在1小时内进行注入后退火，可以形成MoS2。然而，即使在1 cm2的样品面积上发现拉曼信号是均匀的，MoS2层的晶体取向是随机的，因此在项目中需要单晶金属薄膜和衬底，以便在退火时诱导TMDC层的外延生长。该项目围绕5个工作包（wp）构建。由IKS（比利时核与辐射物理研究所）领导的WP1研究衬底制备（包括VSM（比利时固体物理与磁性实验室）和IKS的过渡金属外延沉积）和离子注入（IKS）。由FHI （Fritz-Haber-Institut, Berlin）领导的WP2致力于通过FHI的x射线光电子能谱（XPS）和CNRS （CNRS- ecole polytechnique, France）的原位高分辨率透射电子显微镜（HR-TEM）的原位观察来研究植入后退火。由CNRS领导的WP3致力于合成TMDC材料的非原位物理表征，使用TRT（法国泰利斯研究与技术公司）的拉曼光谱和光致发光，FHI的XPS（用不同的光子能量测量深度剖面），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组。由TRT引导的WP4对应于由TRT制造的场效应晶体管结构的TRT和CNRS的电子（载流子迁移率）和光电子表征。CNRS领导的WP5致力于项目管理、成果开发以及与石墨烯旗舰（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).