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

Abstract Twisted bilayer (TB) MoS2has 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 twisted bilayer MoS2 with different angle. Hence direct one-step synthesis of MoS2 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 twisted bilayer and trilayer of MoS2 by a countercurrent physical vapor deposition (PVD) method. We investigated the evolution of optical properties of twisted MoS2 at the range from 0◦ to 60◦. Raman and photoluminescence (PL) results show a strong relationship between interlayer coupling and the twisted angle of bilayer MoS2. Moreover, interlayer exciton was observed in twisted bilayer MoS2 for a large twisted angle range below 253 K. In comparison, no interlayer exciton related emission was observed for transferred bilayer MoS2, indicating that bottom-up growth of twisted MoS2 presents better interlayer quality. Our results demonstrate a simple approach to produce twisted angle MoS2with high quality for twist-angle based optical and electronic properties investigations.