Presentation Information
[2P50]MBE growth and characterization of ultrathin Bi films on monolayer MOCVD-MoS2
*Toshiro Osawa1,2, Takahiro Nagata2, Yoshiki Sakuma2, Shingo Takezawa1,2, Masato Kotsugi1, Naoka Nagamura1,2 (1. Tokyo University of Science, 2. National Institute for Materials Science)
We report the molecular beam epitaxy (MBE) growth of ultrathin bismuth (Bi) films on monolayer MOCVD-grown MoS2 and their structural and chemical characterization. This work addresses the issue of high contact resistance in two-dimensional (2D) TMDC-based devices, often caused by Fermi level pinning. Bi has been proposed as a contact material to suppress this effect, but its growth behavior on MoS2 remains unclear. We developed a method to estimate Bi film thickness from reflection high-energy electron diffraction (RHEED) patterns using machine learning techniques such as non-negative matrix factorization and principal component analysis. RHEED results showed that Bi grows epitaxially on MoS2 and undergoes a structural transition from a layered phase to a bulk-like structure as thickness increases. Hard X-ray photoelectron spectroscopy (HAXPES) on 7 nm Bi/MoS2 samples revealed no significant chemical modification of the MoS2 layer. These findings suggest that Bi can form ultrathin films on MoS2 without degrading the interface, showing promise for future 2D device applications.