講演情報
[24a-31B-2]Electronically tunable surface adsorption on point defects in hexagonal boron nitride for precursors of tungsten disulfide: a theoretical study
〇Zeyuan Ni1, Takashi Matsumoto1, Kazuyoshi Matsuzaki1, Masaaki Matsukuma1 (1.Tokyo Electron Technology Solutions, Ltd.)
キーワード：
point defect、surface adsorption、semiconductor
2D transition metal dichalcogenides (TMDC) like MoS2 and WS2 are gathering attention from both academic and industrial fields for their high carrier mobility and potential application as channel materials for the next generation field effect transistors. However, they need protective substrates and encapsulations like hexagonal boron nitride (h-BN) to achieve their theoretical performance, hence the film formation of TMDC onto h-BN is an important direction for process integration of device fabrication. In this work, by using density functional theory, we study the adsorption energy (Eads) of a typical set of precursors for WS2 deposition, WF6 and H2S, on h-BN with charged nitrogen vacancies (VN) and boron vacancies (VB). Pristine h-BN is chemically inert and hard to react with WF6 or H2S. On VN and VB, we find that the adsorption energies of WF6 and H2S depends not only on the defect type, but also on the charge state. WF6 interacts strongly with VN at neutral and -1 charge states (VN0 and VN-1), but interacts very weakly with VN at +1 charge state (VN+1) just like on pristine surface. Specifically, dissociation of F atom in WF6 will happen on VN0 and VN-1, but not on VN+1. We believe such behavior originates from the difference in occupation of defect states at different charge states. Similarly, H2S also has charge-dependent Eads on both VN and VB. Since the charge state of defects is tunable by shifting of the Fermi level, the adsorption of WF6 and H2S on these point defects should be electronically tunable. Such electronically controllable surface reaction may be found in other 2D or 3D surfaces. It may have wide application in thin film formation and lead to new types of deposition control methods.