The effect of boron on the structure and conductivity of thin films obtained by laser ablation of diamond with deposition at 700$^\circ$C

Structural features of CB$_ x$ films obtained by pulsed laser ablation of targets made of pressed diamond powder with boron-powder additions at B/C atomic ratio of $x$ = 0.33 have been studied. The films were deposited on heated substrates, so that diffusion processes involving C and B atoms on the surface and in the volume of films were possible. Selected conditions of film deposition ensured their effective doping with boron (0.4 $\le x \le$ 0.6). The incorporation of B atoms was accompanied by the formation of B–C chemical bonds, whereas the formation of $sp^2$ graphite bonds and their ordering in clusters with laminar packing was suppressed. The films possessed very low resistivity ($\sim$1.4 m $\Omega$ cm) at room temperature and exhibited metallic type of conductance on decreasing the temperature to 77 K.