Borazine Promoted Growth of Highly Oriented Thin Films

We report on a phenomenon, where thin films sputter-deposited on single-crystalline Al₂O₃(0001) substrates exposed to borazine─a precursor commonly used for the synthesis of hexagonal boron nitride layers─are more highly oriented than those grown on bare Al₂O₃(0001) under the same conditions. We observed this phenomenon in face-centered cubic Pd, body-centered cubic Mo, and trigonal Ta₂C thin films grown on Al₂O₃(0001). Interestingly, intermittent exposure to borazine during the growth of Ta₂C thin films on Ta₂C yields better crystallinity than direct deposition of monolithic Ta₂C. We attribute these rather unusual results to a combination of both enhanced adatom mobilities on, and epitaxial registry with, surfaces exposed to borazine during the deposition. We expect that our approach can potentially help improve the crystalline quality of thin films deposited on a variety of substrates.