(a) TIC: Double images A and B of a 130 nm high rectangular object, upper left box: phase difference between beams 1 and 2 depends on the height h of the object, upper right box: reference phase difference zero on the background, the sample surface (upper right box) next to the object to be profiled defines the reference phase. N: complex refractive index. (b) Measurement of the phase shift.
(a) Graphene flakes in bright field contrast, dashed line marks the cross section to be measured by interference contrast. (b) The same field of view in bright field with shearing prism: the sheared images are overlaid with lateral shift. Recorded with optical band pass filter 550 ± 20 nm.
(a) Interference contrast image and (b) height profile corresponding to the dashed line across the graphene flake of Fig. 2 , height profile obtained out of the phase profile by means of the optical model. (c) Raman measurements of the mono- and bilayer part of the flake given in (a). The shape and intensity ratio of the peaks are characteristic for mono- and bilayer graphene.
(a) SEM of graphene layer stack on conductive silicon with 2 nm native SiO2 with In-Lens Energy selective Backscatter-detector (EsB), EHT 1.5 kV, grid bias 1.2 kV, optical phase profile (not shown) measured along dashed line, height measured by AFM in vacuum at position A: 9.0 nm and at position B: 13.5 nm with respect to background. (b) Optical phase as a function of graphene layer stack height, the complex refractive index N is the model parameter adjusted, in order to fit the measured phases in positions A: 5° and B: 10.6°. (c) phase profile converted into height of graphene stack by the phase function (black line) in Figure 4(b) .
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