Tuning Interlayer Coupling in Large-Area Heterostructures with CVD-Grown MoS₂ and WS₂ Monolayers

Abstract

Band offsets between different monolayer transition metal dichalcogenides are expected to efficiently separate charge carriers or rectify charge flow, offering a mechanism for designing atomically thin devices and probing exotic two-dimensional physics. However, developing such large-area heterostructures has been hampered by challenges in synthesis of monolayers and effectively coupling neighboring layers. Here, we demonstrate large-area (>tens of micrometers) heterostructures of CVD-grown WS2 and MoS2 monolayers, where the interlayer interaction is externally tuned from noncoupling to strong coupling. Following this trend, the luminescence spectrum of the heterostructures evolves from an additive line profile where each layer contributes independently to a new profile that is dictated by charge transfer and band normalization between the WS2 and MoS2 layers. These results and findings open up venues to creating new material systems with rich functionalities and novel physical effects.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…Van der Waals (vdW) heterostructures composed of 2D layered materials have been attempted intensively recently due to the novel physical properties covering a wide range of electronic, optical, and optoelectronic systems 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242. Jo and co‐workers130 synthesized polymorphic 2D tin‐sulfides of either p‐type SnS or n‐type SnS 2 via adjusting hydrogen during the process.…”

Long-Lived Direct and Indirect Interlayer Excitons in van der Waals Heterostructures

“…The top monolayer of WSe2 is stacked onto the lower MoSe2 using a viscoelastic dry stamping method [51,52], such that the crystal axes are rotationally aligned with a precision of about 1°. The HS are heated in vacuum (<10 -2 mbar, 150°C, 12h) to remove trapped residues in the van der Waals gap between the two crystals and to enlarge the coupling between the layers [53]. The HS is placed on optically inactive, ultra-smooth glass substrates made from Schott borofloat®33.…”

Vibrational spectrum renormalization by enforced coupling across the van der Waals gap betweenMoS2andWS2Fan1, Zhu2, Ke3 et al. 2015Phys. Rev. BSelf Cite321221View full textAdd to dashboardCite

“…The MoS 2 and WS 2 monolayers were grown by a well-established chemical vapor deposition (CVD) technique onto SiO 2 /Si substrates. 13,14 The WS 2 /MoS 2 hetero-bilayers were prepared using polydimethylsiloxane (PDMS) stamping technique as described in previous reports. 14 Briefly, PDMS was spin coated on CVD grown monolayer WS 2 /SiO 2 /Si, and cured at 120 °C for >3 h. The PDMS/WS 2 was released from the SiO 2 /Si substrate by mildly etching SiO 2 in 2 mol/L KOH solution for 0.5 ~ 2 h. It was then rinsed in DI water to remove the KOH residue, and transferred onto CVD grown monolayer MoS 2 /SiO 2 /Si substrate, as shown in the Inset of Fig.1(a).…”