Strong exciton-photon coupling in large area MoSe₂ and WSe₂ heterostructures fabricated from two-dimensional materials grown by chemical vapor deposition

Abstract

Two-dimensional semiconducting transition metal dichalcogenides embedded in optical microcavities in the strong exciton-photon coupling regime may lead to promising applications in spin and valley addressable polaritonic logic gates and circuits. One significant obstacle for their realization is the inherent lack of scalability associated with the mechanical exfoliation commonly used for fabrication of two-dimensional materials and their heterostructures. Chemical vapor deposition offers an alternative scalable fabrication method for both monolayer semiconductors and other two-dimensional materials, such as hexagonal boron nitride. Observation of the strong light-matter coupling in chemical vapor grown transition metal dichalcogenides has been demonstrated so far in a handful of experiments with monolayer molybdenum disulfide and tungsten disulfide. Here we instead demonstrate the strong exciton-photon coupling in microcavities composed of large area transition metal dichalcogenide/hexagonal boron nitride heterostructures made from chemical vapor deposition grown molybdenum diselenide and tungsten diselenide encapsulated on one or both sides in continuous few-layer boron nitride films also grown by chemical vapor deposition. These transition metal dichalcogenide/hexagonal boron nitride heterostructures show high optical quality comparable with mechanically exfoliated samples, allowing operation in the strong coupling regime in a wide range of temperatures down to 4 Kelvin in tunable and monolithic microcavities, and demonstrating the possibility to successfully develop large area transition metal dichalcogenide based polariton devices.

Nonlinear interactions of dipolar excitons and polaritons in MoS2 bilayers

“…Excitons in two-dimensional transition metal dichalcogenides (TMDs) have large oscillator strengths and binding energies [23], making them attractive as a platform for studies of strong light-matter coupling in optical microcavities [6][7][8][9]. A variety of polaritonic states have been realised using monolayers of MX 2 (M=Mo, W; X=S, Se) embedded in tunable [7,9,10,24] and monolithic microcavities [16,[25][26][27][28].…”

Microcavity exciton polaritons at room temperature

“…Compared with the mechanical exfoliation technique, chemical vapor deposition (CVD) provides a scalable fabrication method for the deposition of 2D materials with wafer size, and thus is extremely attractive for the realization of in-plane devices. In 2020, Gillard et al observed strong exciton-photon coupling in a wide range of temperatures, based on microcavities composed of high-quality TMD monolayers encapsulated with large-area hBN [378] . These heterostructures are fabricated using CVD techniques and show high optical quality, comparable to mechanically exfoliated samples.…”

High-throughput dry transfer and excitonic properties of twisted bilayers based on CVD-grown transition metal dichalcogenides

“…22 The other is the preparation of 2D materials by direct vapor-phase growth rather than by mechanical exfoliation. [23][24][25][26][27] In particular, recent advances in chemical vapor deposition (CVD) growth enable the preparation of large-area polycrystalline lms and single crystals of TMDC monolayers on a wafer-scale substrate. [28][29][30][31] In addition, triangular single crystals of TMDCs enable easy determination of the crystal orientation, allowing easy control of twist angles.…”

“…Indeed, the use of such CVD-grown polycrystalline TMDC lms and single crystals has recently enabled fast, continuous fabrication of vdW heterostructures. [23][24][25][26][27] For example, Mannix et al demonstrated the fabrication of solid materials consisting of 80 layers of MoS 2 and twist-controlled 4-layer WS 2 , respectively, by using a robotic assembly with a multi-component polymer stamp. 26 Despite these great advances, there have been only a few reports on dry transfer and its effect on the optical properties of CVDgrown TMDCs.…”