Abstract
Cubic boron nitride (c-BN) thin films are of significant interest
because of their diamond like structure and properties. c-BN shows
high thermal conductivity, chemical inertness against ferrous metals
even at high temperatures, wide band gap, and good transmittance
over a wide spectral range from UV to visible. Applications of c-BN
include hard protective coatings for cutting tools, in optical instruments
as UV detectors, as emitters, and in high temperature electronic
devices. However, synthesis of phase pure c-BN thin films continues
to be very challenging. The present study reviews the current status
of the synthesis, characterisation, mechanical, electrical, and optical
properties of c-BN thin films. Both physical and chemical vapour
deposition methods used for the preparation of the c-BN films are
covered. In addition, different nucleation and growth models of c-BN
formation and growth on different substrates are described. The influence
of process parameters such as ion energy, growth temperatures, chemical
precursors, bias, and impurities on the nucleation and growth is
reviewed. Mechanical properties including hardness, elastic modulus,
and stiffness of c-BN films are discussed. The latest developments
in electrical properties of the c-BN films based on metal?insulator?semiconductor
(MIS) hetero-structures, interface states, impurity states, conduction
mechanism, field emission properties, and negative electron affinity
(NEA) are presented. The optical properties and cathodoluminescence
characteristics of BN films are also discussed.
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