Figure 1
From: Hexagonal boron nitride nanomechanical resonators with spatially visualized motion
Crystal structure of hexagonal boron nitride (h-BN) and basic characteristics of h-BN nanomechanical resonators. (a) Top view of h-BN crystal structure. The box outlined with a blue dashed line illustrates AA′ stacking of the h-BN layered structure. (b) Tilted side view of the h-BN crystal structure. (c) Optical contrast of two-dimensional (2D) crystals, h-BN, graphene (Gr), and MoS2, on a PDMS/glass substrate. The faint lines show the calculated contrast, and the thick solid lines show the exponential fitting as the backbone contrast curve of the corresponding material. (d) and (e) Optical microscopy images of an h-BN and a MoS2 flake on an PDMS/glass substrate with red and cyan dashed lines indicating the 20-layer h-BN and monolayer MoS2 region, respectively. The brightness of the images is enhanced by 40%, and the scale bars are 5 μm. (f) Dependence on the thickness of the averaged absolute contrast (540–560 nm wavelength range) for graphene and h-BN on a PDMS/glass substrate. (g) Optical microscopy image of Device #1, a doubly clamped h-BN resonator suspended over a microtrench 3 μm wide. Scale bar is 10 μm. The h-BN flake before transfer is shown in d. (h) Atomic force microscopy (AFM) traces of Device #1 corresponding to the dashed lines shown in the inset, that is, the AFM image of the dashed line box area in (g). The thickness of the h-BN obtained from the traces is 6.77±0.33 nm. (i) and (j) Optical image and AFM traces of the circular drumhead h-BN resonator, Device #2, respectively. The thickness of h-BN is 9.84±0.40 nm. Scale bar is 10 μm.
