In-depth characterization of stacking faults forming during the growth of Transition-Metal Di-Chalcogenides (TMDCs) by ambient pressure-CVD

Abstract

Transition-metal di-chalcogenides (TMDCs) are van der Waals (vdW) layered materials with unique properties, important for the semiconductor industry. Generally, MX2 (where M = metal and X = chalcogen atoms, such as S, Se, or Te) type TMDCs contain easily exfoliable layers, turning to essentially 2D materials. Planar structural defects, such as stacking faults (SFs), change the atomic arrangement, further improving electronic properties, making these materials useful for various applications (optoelectronic devices, spintronics, gas sensing, catalysis, energy storage, thermoelectrics, etc.) Previous reports on TMDC synthesis with specific SFs highlight the challenge in obtaining them. Even more, for a successful application, these SFs should be stable and consistent under experimental conditions. Our previous work on facile preparation of 2H-WSe2 on W foil in an ambient-pressure chemical vapor deposition (APCVD) exhibited inherent selenium vacancies forming during the synthesis. In current research, we present detailed characterization of SFs forming during this synthesis in various 2H structures: (tungsten di-selenide) WSe2, (molybdenum di-selenide) MoSe2 and (tungsten di-sulfide) WS2. The stability of these defects as a function of post-annealing treatments is also discussed.