Optical and electrical properties of C+-implanted amorphous diamond-like carbon films

Optical and electrical properties of diamond-like carbon (DLC) films irradiated by C+ ions with energy 20 keV in the dose range from 1 x 10(14) to 1.2 x 10(17) cm(-2) were investigated. It was shown that the dependence of the optical gap E-g on the irradiation dose D can be explained by radiation-stimulated growth of pi-clusters. The temperature dependence of the electroresistivity of implanted DLC films in the range of 20-300 K was fitted by the expression R(T) proportional to exp(T-0/T)(n), where 1/4 less than or equal to n less than or equal to 1/2. This indicates the variable range hopping mechanism of conductivity. The analysis of the kinetics of the change of T-0 with irradiation dose also suggested that the size of pi-clusters increases, which agrees with the conclusion made from optical measurements.