▎ 摘　　要

We report new findings on the chemical vapor deposition (CVD) of monolayer graphene with negligible defects (>= 95% negligible defect-peak over 200 mu m x 200 mu m areas) on evaporated copper films. Compared to copper foils used in the CVD of graphene, several new unexpected results have been observed including high-quality monolayer synthesis at temperatures <900 degrees C, a new growth window using a hydrogen-free methane precursor for low-defects, and electron microscope evidence of commensurate growth of graphene grains on underlying copper grains. These thermal, chemical, and physical growth characteristics of graphene on copper films can be attributed to the distinct differences in the dominant crystal orientation of copper films (111) versus foils (100), and consequent dissimilar interplay with the precursor gas. This study suggests that reduced temperature, hydrogen-free synthesis of defect-negligible monolayer graphene is feasible, with the potential to shape and scale graphene grains by controlling the size and crystal orientation of the underlying copper grains.