Using CH4/H-2 source gases, vertically aligned carbon nanotubes were grown on a Cr film by microwave plasma chemical vapor deposition. The Cr film on a silicon wafer had a constant thickness of 100 nm, and bias-enhanced H, plasma pre-treatment was performed for various periods to modify the surface of the Cr film. Bias voltage of - 150 V was applied during both pre-treatment and growth steps, the resultant carbon nanotubes on a Cr film, which had been pretreated in bias-enhanced H-2 plasma for 5 min were vertically aligned. The field emission properties of the resultant carbon nanotubes included an emission current of 0.305 mA at 2 V/mum; and a turn-on field of 1.7 V/mum. (C) 2003 Elsevier B.V. All rights reserved.