SEM images comparing the bright and dark sides of HfO
nanosheets. (a) Wide view image of a curled sheet with a portion broken off. Bright and dark sides are both visible. (b) Close-up of the bright side. The surface has a lot of texture and contains micron scale clusters. Small dark circles can also be seen. (c) Close-up view of dark side. Surface is much smoother, although some particulate is attached. Small dark circles are again visible, measuring about 100 nm in diameter.