Jin-Woo Jung, Hyeon-Seo Choi, Young-Jun Lee, Youngjae Kim, Takashi Taniguchi, Kenji Watanabe, Min-Yeong Choi, Jae Hyuck Jang, Hee-Suk Chung, Dohun Kim, Youngwook Kim, Chang-Hee Cho
Hexagonal boron nitride (h-BN) is a key ingredient for various 2D van der Waals heterostructure devices, but the exact role of h-BN encapsulation in relation to the internal defects of 2D semiconductors remains unclear. Here, it is reported that h-BN encapsulation greatly removes the defect-related gap states by stabilizing the chemisorbed oxygen molecules onto the defects of monolayer WS2 crystals. Electron energy loss spectroscopy (EELS) combined with theoretical analysis clearly confirms that the oxygen molecules are chemisorbed onto the defects of WS2 crystals and are fixated by h-BN encapsulation, with excluding a possibility of oxygen molecules trapped in bubbles or wrinkles formed at the interface between WS2 and h-BN...
March 17, 2024: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)