Edge‐Assisted Epitaxy of 2D TaSe2‐MoSe2 Metal–Semiconductor Heterostructures and Application to Schottky Diodes

Abstract Van der Waals (vdWs) heterostructures based on 2D metals and semiconductors have attracted considerable attention due to their excellent properties and great application potential in next‐generation electronic and optoelectronic devices. To obtain such vdWs heterostructures, the conventional approach with artificial exfoliation and stacking of 2D metals onto 2D semiconductors in the vertical direction is still far from satisfactory, because of the low yield and impurity‐involved transfer process. Here, two‐step vapor deposition growth of 2D TaSe 2 ‐MoSe 2 metal–semiconductor heterostructures is reported. Raman maps confirm the precise spatial modulation of the as‐grown 2D TaSe 2 ‐MoSe 2 heterostructures. Structural analysis reveals that the upper 1T‐TaSe 2 is formed heteroepitaxially on/around the presynthesized 2H‐MoSe 2 monolayers with an epitaxial relationship of (10‐10) TaSe2 //(10‐10) MoSe2 and [0001] TaSe2 //[0001] MoSe2 . Based on the detailed characterizations of morphology, structure, and composition, an edge‐induced growth mechanism is proposed to illustrate the formation process of the 2D heterostructures, confirmed by first‐principle calculations. In addition, Kelvin probe force microscope characterizations and electrical transport measurements confirm that the 2D metal–semiconductor heterostructures exhibit typical rectification characteristics with a contact potential height of ≈431 mV. The direct growth of high‐quality 2D metal–semiconductor heterostructures marks an important step toward high‐performance integrated optoelectronic devices.