Comparison of the effect of boron and nitrogen incorporation on the nucleation behavior and electron-field-emission properties of chemical-vapor-deposited diamond films

Effect of boron (or nitrogen) doping on the nucleation behavior of chemical-vapor-deposited diamond films was investigated. It is observed that inclusion of B(OCH₃)₃ species in gases markedly enhances, whereas addition of (NH₃)₂CO species pronouncedly retards the nucleation of diamonds. Raman spectroscopic analyses reveal that the probable mechanism is the formation of boron-carbon clusters due to boron incorporation. While the boron (or nitrogen) species incorporated insignificantly modify the microstructure, these dopants markedly alter the electron-field-emission behavior of the diamond films. The field-emission properties are optimized for films grown with B(OCH₃)₃=2 sccm [or (NH₃)₂CO=6 sccm]. The nitrogen-doped films exhibit significantly superior electron-field-emission capacity to the boron-doped films, even though the latter possess much lower electrical resistivity [viz. (J_e)_n=1020 μ A/cm², (ρ)_n=76 mΩ cm and (J_e)_b=360 μ A/cm², (ρ)_b=2.1 mΩ cm].