Formation of p-type semiconducting ultrananocrystalline diamond/hydrogenated amorphous carbon composite films by boron doping

p-Type ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films were fabricated by pulsed laser deposition using boron-doped graphite targets. Thermal analysis confirmed the occurrence of p-type conduction. The electrical conductivity increased with the doped amount of boron. An activation energy estimated from the Arrhenius plot was approximately 0.1 eV. Near-edge X-ray absorption fine structure spectra revealed that the σ*C-H peak weakened and the σ*C-B peak strengthened with an increase in the doped amount of boron. Fourier transform infrared spectroscopy showed that the sp³ C-H peak weakened with the doped amount of boron. These probably indicate that the hydrogen atoms that terminate the dangling bonds of UNCD crystallites are partially replaced with boron atoms.