composition, morphology, stress and number of layers. Monitoring graphene's G and D peaks (around 1580 and 1360 cm−1) intensity gives direct information on the number of layers of the sample. It has been shown that the two graphene layers can withstand important strain or doping mismatch which ultimately should lead to their exfoliation. Quantitative determination of bilayer graphene's structural parameters---such as surface roughness, inter- and intralayer spacings, stacking order, and interlayer twist---is obtainable using 3D electron diffraction References Allotropes of carbon Emerging technologies Group IV semiconductors Graphene