High-pressure phases of boron nitride grown by laser-assisted plasma chemical vapor deposition from BCl3+NH3+H2+Ar

Abstract

By using a newly designed collimated plasma beam reactor, plasma-enhanced chemical vapor deposition from BCl3+NH3+H2+Ar with the surface irradiated by a 193-nm excimer laser at a pressure of 2.8 Torr and substrate temperatures of 500–900 °C yielded BN films with the following texture as revealed by transmission electron diffractometry (TED), transmission electron microscopy, scanning electron microscopy, and Fourier-transformed infrared spectroscopy: (1) a thin-film part which consists of 10-nm-sized crystallites with a sp2-bonded structure grown on the substrate, namely, a sp2 100 Å layer; (2) polycrystalline parts with cBN or wBN structure, depending on the condition, embedded in a sp2 100 Å layer; (3) crystallites, though found infrequently, grown to be much larger than the sp2 100 Å layer thickness. The TED pattern of the polycrystalline wBN was particularly in agreement with the standard data.