Amorphous carbon thin films were deposited by LF (100 kHz), RF (13.56MHz), and pulsed RF (13.56MHz) plasma CVD with DC self-bias voltage of .300 V and 50 mTorr on Si wafers at 15 oC using a mixture of methane and hydrogen for comparing structural properties of the deposited films in an asymmetric plasma reactor. The surface morphologies of the deposited films were observed by Atomic force microscopy (AFM). The average roughness (Ra) analyzed by AFM data was 4.03, 1,84, 1.52 A at LF (100 kHz), RF (13.56 MHz), and pulsed RF (13.56MHz) plasma, respectively. From these results, the films deposited by pulsed RF plasma have more smooth and dense surface compared with those deposited by LF (100 kHz), and RF (13.56MHz) plasma. The ratios of ID/IG obtained from Raman data were 2.69, 0.76 and 0.44 at LF (100 kHz), RF (13.56 MHz), and pulsed RF (13.56 MHz) plasma, respectively. It is concluded that the film deposited by pulsed RF plasma has more diamond-like properties compared with that deposited by LF (100 kHz), and RF (13.56 MHz) plasma.