Nanowerk April 11, 2024
The exact role of h-BN encapsulation in relation to the internal defects of 2D semiconductors in hexagonal boron nitride (h-BN) remains unclear. An international team of researchers (South Korea, Japan) reported that h-BN encapsulation greatly removes the defect-related gap states by stabilizing the chemisorbed oxygen molecules onto the defects of monolayer tungsten disulfide (WS2) crystals. Studies showed that h-BN encapsulation prevented the desorption of oxygen molecules over various excitation and ambient conditions, resulting in a greatly lowered and stabilized free electron density in monolayer WS2 crystals. This suppressed the exciton annihilation processes by two orders of magnitude compared to that of bare WS2. The valley polarization became robust against the various excitation and ambient conditions in the h-BN encapsulated WS2 crystal… read more. Open Access TECHNICAL ARTICLE
a) Schematic illustration showing the chemisorbed oxygen molecules anchored… Credit: Advanced Science, 17 March 2024