Electrical observation of subband formation in graphene nanoribbons

We report the experimental observation of subband formation in graphene nanoribbons, where conductance becomes quantized due to the lateral quantum confinement. We show that this quantization in graphene nanoribbons can be observed at temperatures as high as 80 K and channel lengths as long as 1.7 mu m. The observed quantization is in agreement with that predicted by theoretical calculations.