Figure 5. Identification of number of layers by fitted Raman features.

(a) Energy difference between the A_1g and the E_2g modes saturates to bulk value in inversely exponential manner (b) relative intensity ratio of the E_2g peak to the A_1g peak in Raman spectrum shows linear relationship with increasing layer number (c) Signal-to-noise ratio of Raman spectrum improves with increasing layer number due to interference enhancement and starts to decline towards bulk value after passing through maximum point at certain layer number.