Substrate roughness and crystal orientation-controlled growth of ultra-thin BN films deposited on Cu foils

This work demonstrates the synthesis of boron nitride (BN) films by reactive radio-frequency (RF) magnetron sputtering over the copper foil. Copper foil preparation conditions determine the phase selectivity of BN films and the growth of continuous films. Discontinuous films are observed for Cu foils with high surface roughness. Deposition of BN on non-electropolished Cu foils with a predominant (100) orientation and high surface roughness, resulted in the growth of discontinuous BN islands with mixed cubic and hexagonal BN phases. On Cu foils having (100) and (110) orientations with grain sizes (100 mu m) and low surface roughness, the growth of cubic BN (cBN) films is observed. While on electropolished Cu foils with (111) surface orientation, similar grain sizes, and low surface roughness (about 5 nm), we get the growth of continuous hexagonal BN films. The current-voltage (I-V) response of the hBN films showed a rectifying behavior. This work would be beneficial to researchers who are investigating the epitaxial growth of BN films metal substrates. [GRAPHICS] .