  A foundation of the modern technology that uses single-crystal silicon has
been the growth of high-quality single-crystal Si ingots with diameters up to
12 inches or larger. For many applications of graphene, large-area high-quality
(ideally of single-crystal) material will be enabling. Since the first growth
on copper foil a decade ago, inch-sized single-crystal graphene has been
achieved. We present here the growth, in 20 minutes, of a graphene film of 5 x
50 cm2 dimension with > 99% ultra-highly oriented grains. This growth was
achieved by: (i) synthesis of sub-metre-sized single-crystal Cu(111) foil as
substrate; (ii) epitaxial growth of graphene islands on the Cu(111) surface;
(iii) seamless merging of such graphene islands into a graphene film with high
single crystallinity and (iv) the ultrafast growth of graphene film. These
achievements were realized by a temperature-driven annealing technique to
produce single-crystal Cu(111) from industrial polycrystalline Cu foil and the
marvellous effects of a continuous oxygen supply from an adjacent oxide. The
as-synthesized graphene film, with very few misoriented grains (if any), has a
mobility up to ~ 23,000 cm2V-1s-1 at 4 K and room temperature sheet resistance
of ~ 230 ohm/square. It is very likely that this approach can be scaled up to
achieve exceptionally large and high-quality graphene films with single
crystallinity, and thus realize various industrial-level applications at a low
cost.
