Title of Paper:Growth and characterization of porous sp(2)-BN films with hollow spheres under hydrogen etching effect via borazane thermal CVD

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Date of Publication:2018-09-15

Journal:APPLIED SURFACE SCIENCE

Included Journals:SCIE

Volume:452

Page Number:314-321

ISSN No.:0169-4332

Key Words:Porous sp(2)-BN films; Chemical vapor deposition; Nucleation

Abstract:Porous sp(2)-boron nitride (sp(2)-BN) films were directly grown on c-plane Al2O3 substrates by low pressure thermal chemical vapor deposition (CVD) using borazane (NH3-BH3) as a single precursor and without any catalyst. It was found that the BN films grown under 20 mbar are porous and consist of nanoscaled hollow BN spheres of various sizes, with outer radius (r(o)) ranging from 7.20 nm to 13.32 nm. The B-N bonding was confirmed to be sp(2) -bonded by the Raman scattering whereas, the crystal structure was determined by TEM and XRD to be turbostratic BN (t-BN) having a lattice constant 'c' larger than the hexagonal BN (h-BN) bulk crystal. Homogenous nucleation played a vital role in the porous sp(2)-BN formation that is contrary to normal CVD growth under such low pressure i.e. 2 mbar for denser BN films. Additionally, because of the H-2 chemical etching effect, the H-2/N-2 ratio shows a strong influence on the film growth. All of the as-grown films have shown good ultraviolet (UV) absorption edge near 210 nm, hence providing a feasible route towards the synthesis of porous sp(2)-BN with higher surface-volume ratio for high performance photo sensors and smart energy storage devices. (C) 2018 Elsevier B.V. All rights reserved.