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.

Synthesis of Nb‐Doped‐WS2–NbS2: A Degenerate‐Semiconductor–Metal Heterostructure

“…[25] From the SAED pattern results, we concluded that our samples grew along both lateral and vertical architectures. This growth phenomenon has been observed in other heterostructures, such as TaSe 2 -MoSe 2 [27] and SnS-SnS x Se (1−x) . [39] Figure 4i shows a high-resolution ADF-STEM image of the NbS 2 layer with a perfect hexagonal arrangement.…”

“…CVD is an efficient method for producing high-quality interfaces with controllable thicknesses on a large scale. Two-step CVD growth serves as a universal method for growing diverse M-S TMDs heterostructures, such as NbS 2 -MoS 2 , [24] NbS 2 -WS 2 , [25,26] TaSe 2 -MoSe 2 , [27] NbTe 2 -WSe 2 , [28] and VSe 2 -WSe 2 . [29] However, the edges and surface of the as-grown first layer can be oxidized in air before the second growth step, inducing an undesirable heterointerface.…”

Synthesis of NbSe2/Bilayer Nb‐Doped WSe2 Heterostructure from Exfoliated WSe2 Flakes

“…[ 23 ] Chemical vapor deposition (CVD) is a widely recognized and efficient technique for the large‐scale production of high‐quality m–s heterostructures. Various m–s heterostructures, such as NbS 2 –MoS 2, [ 24,25 ] NbS 2 –WS 2 , [ 26 ] VSe 2 –WSe 2 , [ 27 ] TaSe 2 –MSe 2 , [ 28 ] and NbTe 2 –WSe 2 , [ 29 ] have been successfully grown by CVD. However, these investigations solely concentrated on heterostructures involving monolayer TMD semiconducting layers.…”

Epitaxial van der Waals contacts of 2D TaSe2-WSe2 metal–semiconductor heterostructures

“…These strategies include manufacturing clean edge contact to 2D semiconductors, 30,31 phase engineering of 2D semiconductors to construct planar metal–semiconductor heterostructures, 32,33 formation of clean interfaces via van der Waals (vdWs) contacts using graphene, 34 mechanical transfer of metal films, 35 using hexagonal boron nitride (h-BN) as the tunnel barrier, 10 and synthesis of metal–semiconductor heterostructures by vapour phase epitaxy. 36–42 Among these strategies, vapour phase epitaxy technology is an effective method to create vdWs heterostructures with a low contact barrier at the clean vdWs interface. For instance, Zhang et al 38 demonstrated a controllable epitaxial growth of NbS 2 -WS 2 lateral heterostructures via a facile “two-step” chemical vapor deposition (CVD) route.…”