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 sigma*-H peak weakened and the sigma*-B peak strengthened with an increase in the doped amount of boron. Fourier transform infrared spectroscopy showed that the sp(3) 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. (C) 2010 The Japan Society of Applied Physics