An innovative design of AFM for easily integrated with optical microscope

The atomic force microscopy (AFM) was proposed to characterize the surfaces of various materials with high sensitivity and resolution(sub-nanometer) since 1980s, but it intrinsically lacks amongst others chemical sensitivity. These limitations of AFM can be overcome by coupling with optical microscope, which allows to obtain more comprehensive characterization data by in-situ measurement. To integrate the AFM into the upright optical microscope easily, this paper proposed a novel design of AFM. The corresponding Raman-AFM system was developed which adopts the sample scanning structure with a self-developed ultra-thin AFM head. The AFM head employs an innovative multi-reflected laser beam to detect the deformation of the cantilever, which greatly reduces the Z-direction thickness of the head, making its Z-direction thickness smaller than the working distance of the objective lens. Therefore, the AFM probe can be directly mounted under the objective lens of the upright optical microscope without changing the existing optical path. To evaluate the performance of the proposed AFM system, a standard grid was imaged using the Raman-AFM system. Then, a sample of two-dimensional material, black phosphorus(BP)/molybdenum disulfide(MoS2) heterojunction, was characterized. The physicochemical information of the heterojunction was obtained by in-situ measurement of the surface topography and Raman spectra.