Development of a Capping Layer for Air-Stable 2D WTe2 Materials

Two-dimensional tungsten ditelluride (2D WTe₂) possesses a rich variety of unconventional properties, which are particularly promising for fundamental studies of topologically nontrivial states and their potential applications in advanced electronics and quantum technologies. Given that the majority of future applications rely on stable charge transport characteristics, the susceptibility of WTe₂ to oxidation under ambient conditions presents a significant challenge, limiting its practical use. In this study, we present an innovative inorganic polysilazane capping layer that can be converted to silica to effectively isolate 2D WTe₂ structures from oxygen and water. Additionally, WTe₂ surface passivation with n-hexylamine is also tested. Charge transport measurements at low temperatures for as-grown, polysilazane-capped, and n-hexylamine-functionalized structures demonstrate that the developed inorganic polysilazane capping layer efficiently protects from oxidation in an ambient environment, thereby allowing 2D WTe₂ to maintain its structural integrity and electronic characteristics over extended periods.