Pardon my ignorance, but why does the "447 TB/cm^2" density value use square centimeters instead of a volume unit? Does the information capacity of this material really scale in proportion to area? How? Or is it just a typo?
fluorographane is a single atomic layer — one carbon thick — so storage density is naturally per unit area. The paper also gives volumetric density for the nanotape spool architecture (0.4–9 ZB/cm³, Section 4.4).