Project title: Optical Characterization of BN Films Grown on Diamond

Cubic boron nitride (cBN) has many potential applications due to its unique combination of excellent physical and chemical properties including: high hardness -second only to diamond; high thermal conductivity; and ability to be doped p- and n- type.  Recent developments have made it possible to fabricate thick (several microns) cBN films grown heteroepitaxially on diamond film substrates, as with other semiconductor applications of thin films, optical characterization techniques are expected to play a major role in the development of future cBN technologies.  However, the current knowledge of the optical properties of cBN films is limited to few scattered reports involving thin films (~200 nm) growth on c-Si substrates with, undesired, amorphous and hexagonal BN (aBN and hBN, respectively) interlayers.  This project will study the optical properties of thick, high quality cBN films grown heteroepitaxially on diamond substrates using spectroscopic ellipsometry (SE).  The dielectric function of cBN deduced from SE in the spectral range from near infrared (0.7 eV) to the ultraviolet (6.5 eV) will be correlated to the mechanical and electrical properties of cBN films and in turn with its phase purity, crystal size, defect density, and stress.  The results obtained from this project will provide the foundations for advanced optical characterization of thick, high quality cBN films that will be beneficial in the development of cBN for electronic applications.

Supervisor: Dr. J. Antonio Zapien (apjazs@cityu.edu.hk)

Suitable for: M. Phil. /Ph.D.

Number of students: 1.