Microscopic evidence of strong interactions between chemical vapor deposited 2D MoS2 film and SiO2 growth template
Woonbae Sohn, Ki Chang Kwon, Jun Min Suh, Tae Hyung Lee, Kwang Chul Roh, Ho Won Jang
Abstract
Abstract Two-dimensional MoS 2 film can grow on oxide substrates including Al 2 O 3 and SiO 2 . However, it cannot grow usually on non-oxide substrates such as a bare Si wafer using chemical vapor deposition. To address this issue, we prepared as-synthesized and transferred MoS 2 (AS-MoS 2 and TR-MoS 2 ) films on SiO 2 /Si substrates and studied the effect of the SiO 2 layer on the atomic and electronic structure of the MoS 2 films using spherical aberration-corrected scanning transition electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The interlayer distance between MoS 2 layers film showed a change at the AS-MoS 2 /SiO 2 interface, which is attributed to the formation of S–O chemical bonding at the interface, whereas the TR-MoS 2 /SiO 2 interface showed only van der Waals interactions. Through STEM and EELS studies, we confirmed that there exists a bonding state in addition to the van der Waals force, which is the dominant interaction between MoS 2 and SiO 2 . The formation of S–O bonding at the AS-MoS 2 /SiO 2 interface layer suggests that the sulfur atoms at the termination layer in the MoS 2 films are bonded to the oxygen atoms of the SiO 2 layer during chemical vapor deposition. Our results indicate that the S–O bonding feature promotes the growth of MoS 2 thin films on oxide growth templates.