| Institution: | 1. Department of Applied Physics, Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P.R. China
These authors contributed equally to this work.;2. Department of Applied Physics, Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P.R. China;3. State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, Guangzhou, P.R. China |
| Abstract: | van der Waals In2Se3 has attracted significant attention for its room-temperature 2D ferroelectricity/antiferroelectricity down to monolayer thickness. However, instability and potential degradation pathway in 2D In2Se3 have not yet been adequately addressed. Using a combination of experimental and theoretical approaches, we here unravel the phase instability in both α- and β′-In2Se3 originating from the relatively unstable octahedral coordination. Together with the broken bonds at the edge steps, it leads to moisture-facilitated oxidation of In2Se3 in air to form amorphous In2Se3?3xO3x layers and Se hemisphere particles. Both O2 and H2O are required for such surface oxidation, which can be further promoted by light illumination. In addition, the self-passivation effect from the In2Se3?3xO3x layer can effectively limit such oxidation to only a few nanometer thickness. The achieved insight paves way for better understanding and optimizing 2D In2Se3 performance for device applications. |
