Optical and electrical characteristics of amorphous diamond films

Amorphous diamond (a-D) films have been formed by magnetic field filtered carbon ion deposition. The optical and electrical characteristics of these films as a function of the substrate bias voltage V-h have been studied using optical absorption spectroscopy and electrical measurements. The results show that a-D films with high sp(3) fractions were formed when the substrate bias voltage V-b was in the range -10 V to -50 V. The optical band gap of such a-D films was found to be larger than 3 eV. It is shown that optical absorption spectroscopy is a simple method to compare qualitatively the sp(3) fractions in carbon films. The mechanisms of transport in these films are also studied and discussed. (C) 1997 Elsevier Science S.A.