Dual ion beam deposited boron-rich boron nitride films

K. F. Chan, Chung Wo Ong, C. L. Choy, R. W.M. Kwok

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)


BNxfilms with N content varying from 2 to 40 at. % were deposited by dual ion beam deposition. The films are solid admixtures of a B-rich phase composed of icosahedral atomic clusters, and a graphite-like boron nitride phase. The fraction of the B-rich phase drops, while that of the graphite-like boron nitride phase grows with increasing N content. The hardness of the films first rises, reaches a maximum value of 18.8 GPa at a N content of 20.2 at. %, and falls with further increase in N content. This rise is explained by assuming that some N atoms are located interstitially at the sites surrounded by icosahedral clusters, such that the hardness of the material is enhanced as a result of additional cross-linking of the network by the N atoms. However, the overall N contents are not sufficient to ensure the two phases to have the ideal stoichiometry of B4N and hexagonal BN (h-BN) structures, so that the B-rich phase in the film does not exhibit the theoretical strongest possible cross-linking that has been proposed for the ideal B4N structure. The drop in the hardness of the films with N contents exceeding 20.2 at. % arises from the increasing volume fraction of the graphite-like boron nitride phase.
Original languageEnglish
Pages (from-to)2944-2949
Number of pages6
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number5
Publication statusPublished - 1 Jan 1999

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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