Van der Waals epitaxy of twisted bilayer and trilayer MoS2 with strong coupling and interlayer exciton emission

Abstract Twisted bilayer (TB) MoS 2 has attracted great interest due to its application in twistronics. A modification of the conventional growth method is usually required to overcome the energy barrier between layers to grow TB MoS 2 with different angle. Hence direct one-step synthesis of MoS 2 with a large area, clean surface, and a wide twisted angle range is still a challenge. In this work, we show the direct growth of high-quality TB and trilayer of MoS 2 by a countercurrent physical vapor deposition method. We investigated the evolution of optical properties of twisted MoS 2 at the range from 0° to 60°. Raman and photoluminescence results show a strong relationship between interlayer coupling and the twisted angle of bilayer MoS 2 . Moreover, interlayer exciton was observed in TB MoS 2 for a large twisted angle range below 253 K. In comparison, no interlayer exciton related emission was observed for transferred bilayer MoS 2 , indicating that bottom–up growth of twisted MoS 2 presents better interlayer quality. Our results demonstrate a simple approach to produce twisted angle MoS 2 with high quality for twist-angle based optical and electronic properties investigations.