Bilayer WSe2 Characterization via AFM, Raman, PL, STEM

AFM analysis was conducted on an atomic force microscope (AFM, Icon Bruker) equipped with a probe with a tip radius of <10 nm (TAP300AI-G, Budgetsensors) to evaluate the height profiles of bilayer WSe₂. Raman and PL spectroscopy were performed under ambient conditions using an ND-MDT spectrometer equipped with a laser excitation wavelength of 532 nm. For STEM imaging, bilayer WSe₂ flakes were transferred onto a holy-carbon TEM grid using a poly(methyl methacrylate) (PMMA)-assisted transfer process.^{58 (link)} STEM was performed with a JEOL ARM 200CF equipped with a CEOS corrector (Cs ~ 100 nm) operating at 80 kV to reduce knock-on damage. Images were acquired with a HAADF detector from 54–220 mrad and cleaned using an average background subtraction filter (ABSF) SAED patterns were acquired with a JEOL F200 TEM operating at 200 kV using a selected-area aperture with an effective size at the sample of ~1 μm.