  The discovery of interfacial ferroelectricity in two-dimensional rhombohedral
(3R)-stacked semiconductors opens up a new pathway for achieving ultrathin
computing-in-memory devices. However, exploring ferroelectricity switching in
natural 3R crystals is difficult due to lack of co-existing 3R stacking
domains. Here, we present that MoS2 homoepitaxial patterns with 3R polytypic
domains can manifest switchable ferroelectricity at room-temperature. Based on
the diffusion limited aggregation theory, such MoS2 patterns are formed under
the low Mo chemical potential and low temperature with respect to common
chemical vapor deposition synthesis. The alternation of 3R polytypes in the
MoS2 homoepitaxial patterns, observed by scanning transmission electron
microscopy, accounts for ferroelectricity switching. The MoS2 field-effect
transistors with 3R polytypic domains exhibit a repeatable counterclockwise
hysteresis with gate voltage sweeping, an indication of ferroelectricity
switching, and the memory window exceeds those measured for compact-shaped 3R
bilayer devices. This work provides a direct growth concept for layered
3R-based ferroelectric memory.
