Vertical electrical field induced island growth in layered TiSe2.

For practical applications of atomically thin transition metal dichalcogenides, it is essential to characterize the structural stability under external stimuli such as electrical fields. Using vacancy monolayer islands on TiSe2 surfaces as a model system, we experimentally and theoretically investigated the shape evolution and growth rate by using scanning tunneling microscopy. The growth rate that depends on the tunneling current is experimentally determined. Our simulations of monolayer island evolution using a phase-field model are consistent with the experimental observations. The results could be potentially important for electronic device applications of ultrathin transition metal dichalcogenides and other 2D materials.