Amorphous C films were prepared under radical-controlled ambience using a photo-enhanced chemical vapor deposition system proposed by the authors and were characterized by various techniques. The deposition system consisted of a CH4/Cl2 mixture and a super-high-pressure Hg lamp, and the deposition temperature ranged from 343 to 573 K. The samples were soft, and their Cl/C and H/C ratios were 0.035-0.09 and below 0.03, respectively. The elemental compositions were examined, referring to the concentrations of gas-phase radicals estimated previously. The sample prepared at 343 K showed a resistivity as high as 2.5 × 108 Ω·cm and an optical band gap of 1.25 eV, both of which decreased with temperature. The sp3/sp2 ratio and the degree of ordering of sp2-bonded atoms were investigated, using the results of TEM, RHEED, XPS, Raman and IR spectra, and optical-gap measurement.