A schematic of hexagonal networks of boron atoms (pink), which are found on the hexagonal nodes and periodically in the center of the hexagon, grown on a surface of copper atoms (brown). The scientists used a low-energy electron microscope (LEEM) to watch "islands" of borophene (yellow triangles in left circle) grow, changing the temperature, deposition rate, and other growth conditions in real time to refine the "recipe." The islands can sit on the surface in six different orientations and can be discriminated by selecting an electron diffraction spot (such as the one circled in yellow) corresponding to a particular orientation (the one connected with the dotted line). Eventually the islands grow to such an extent that they touch and meet, and the entire surface (one centimeter squared) is covered with borophene, as seen in the circle on the right. The colors were added to distinguish regions with different orientations.