Diamond-like amorphous carbon (DAC) films were deposited for field-emission application using supermagnetron plasma by mixing N-2 or H-2 in i-C4H10 gas at the upper and lower electrode rf powers (UPRF/LORF) of 800 W/100-800 W. At an 800 W/800 W, the N-2 (0-80%) gas-mixed DAC films showed an emission threshold electric field (E-TH) of 19 V/mu m. At the 800 W/100 W, the H-2 (20%) gas-mixed DAC film showed low E-TH's of 13 V/mu m, respectively. The moderate reduction of CC and CN double bonds by the decrease of LORF from 800 W to 100 W was found to be effective to lower E-TH. (c) 2006 Elsevier B.V. All rights reserved.