A simple method for fabricating high-quality carbon nanoscrolls (CNSs) by exfoliation of natural flake graphite with the assistance of microwave sparks in liquid nitrogen is demonstrated. Field-effect transistors based on the CNSs show stable ambipolar behavior in both air and nitrogen, with maximum p-type and n-type mobilities in nitrogen of up to 3117 cm(2) V-1 s(-1) and 4595 cm(2) V(-)1 s(-1), respectively.