The de saddle-field glow-discharge technique was employed to deposit undoped, phosphorus-doped and boron-doped hydrogenated diamond-like amorphous carbon films. The undoped films were grown using pure methane, while the doped films were grown using methane diluted with dopant gases (phosphine and diborane) in mole fraction ranging from 0.05 to 1 x 10(-5). Secondary ion mass spectroscopy was used to determine the composition of these films. The results showed that various levels of doping in amorphous carbon films can be achieved predictably by using the appropriate mole fraction of dopant gases. The fractions of tetrahedral and trigonal bonds in the films were obtained using x-ray Auger electron spectroscopy. The optical energy gaps of the films were determined from optical absorption measurements. These data were correlated with the doping levels of the films. The electrical conductivities of the undoped and doped samples were determined at temperatures in the range from 225 to 380 degrees C. The activation energies were determined, and the corresponding conduction mechanisms were examined.