Koçak Yusuf, Gür Emre
Department of Physics, Faculty of Science, Ataturk University, 25250 Erzurum, Turkey.
ACS Appl Mater Interfaces. 2020 Apr 1;12(13):15785-15792. doi: 10.1021/acsami.9b18759. Epub 2020 Mar 20.
Large area 2D WS has been grown successfully by radio frequency magnetron sputtering (RFMS) method. First, in order to investigate the pressure dependence on the grown WS samples, WS were grown at 5 different growth pressures, 5, 10, 15, 20, and 25 mTorr. It has been observed that the surface morphology changes for the samples grown at higher growth pressures, 15, 20, and 25 mTorr. Vertically standing nanowall (NW)-like structures have been formed at these relatively high growth pressures. It has also been observed that the (002) plane is highly dominant, which means layer by layer growth parallel to the substrate, for the sample grown at 20 mTorr. X-ray photoelectron spectroscopy (XPS) measurements revealed an increasing atomic percentage of the S element to W element, S/W, ratio in thin films, as the growth pressure increases. Growth dynamics of WS has been investigated by time-dependent-growth WS samples, 5, 10, 20, 40, and 80 s under 20 mTorr pressure. It has been shown by atomic force microscopy, scanning electron microscopy, and transmission electron microscopy that a highly smooth surface has been achieved in the samples grown for the duration of 5 and 10 s. Raman mapping measurements on the sample grown at 5 s have revealed large area homogeneous growth. As the growth time gets longer, the NWs emerge on the surface at some nucleation points. Only the peak that belongs to the (002) plane has been observed for samples grown at 5 and 10 s by the X-ray diffraction (XRD) measurements. XRD measurements have revealed the appearance of turbostratic peaks of (11) and (10) as the thickness increases. Photoluminescence measurements have indicated near-band-edge emission centered at 630 nm for only 5 and 10 s samples.
通过射频磁控溅射（RFMS）方法已成功生长出大面积二维WS。首先，为了研究生长压力对生长的WS样品的影响，在5种不同的生长压力下，即5、10、15、20和25毫托，生长了WS。已观察到在较高生长压力（15、20和25毫托）下生长的样品，其表面形态发生了变化。在这些相对较高的生长压力下形成了垂直站立的纳米壁（NW）状结构。还观察到，对于在20毫托下生长的样品，（002）面高度占主导，这意味着平行于衬底逐层生长。X射线光电子能谱（XPS）测量表明，随着生长压力的增加，薄膜中S元素与W元素的原子百分比，即S/W比增加。通过在20毫托压力下随时间生长5、10、20、40和80 s的WS样品，研究了WS的生长动力学。原子力显微镜、扫描电子显微镜和透射电子显微镜表明，在生长5秒和10秒的样品中实现了高度光滑的表面。对在5秒时生长的样品进行的拉曼映射测量揭示了大面积的均匀生长。随着生长时间变长，NW在一些成核点出现在表面上。通过X射线衍射（XRD）测量，对于在5秒和10秒时生长的样品，仅观察到属于（002）面的峰。XRD测量表明，随着厚度增加，出现了（11）和（10）的乱层峰。光致发光测量表明，仅5秒和10秒的样品在630 nm处有近带边发射。
