Carbon nanotubes(CNTs) have attracted much attention because of their unique structure and properties since their discovery. One important potential application for the CNTs is as electron field emission sources in cold cathode flat panel displays as electron guns. Although a few of studies on the field emission properties of patterned aligned multi-wall nanotubes (MWNTs) were reported

the catalyst films were patterned by conventional photolithography and etching techniques. This method is too troublesome in application. In this paper

we prepared CNT patterns by a simple method

which is based on laser writing technology. Carbon nanotubes (CNTs) films were grown on patterned Ni lines coated substrate by microwave plasma chemical vapour deposition (MWPCVD). Ni films deposited on ceramics substrates by d.c. magnetron sputtering are used as catalysts for growing the CNTs. The ceramics substrates were mechanically polished using various grinding and polishing powders in order to uniform Ni film. Before growing CNTs

the Ni films were patterned to be lines by laser writing technology and then the CNTs were deposited on the catalyst patterns. The source gas for growing the CNTs was a mixture of H

2

and CH

4

. The gas flow rate of H

2

is 100 sccm

and the growth pressure was 6.5×10

3

Pa

various deposition times were applied to control the length of the carbon nanotubes. Scanning electron microscopy (SEM) was used to determine the morphology of carbon nanotubes. Raman spectroscopy was used to analyze the structure of carbon nanotubes. The field emission characteristics of the samples were measured by using a diode structure. The transparent anode was made of coating phosphor onto an ITO coated glass plate. The CNTsamples as the cathode were separated from the anode by a mica sheet with a suitable hole as the emission area. The gap between the anode and the cathode was 500 μm. The measurement was conducted under pressure of 3.6×10

-5

Pa. By varying process conditions such as Ni layer thickness

gas flow rate

deposition time

reactive temperature

the optimum conditions for field electron emission were found. When gas flow rate of CH

4

was 5 sccm

Ni film thickness was 150 nm

deposition time was 5 min

and reactive temperature was 700～800℃

the field emission properties are best. At this condition

all nanotubes are well aligned as characterized by SEM. Turn-on field of 1.3 V/μm

emission current density of 6.8 mA/cm

2

and field enhancement factor of 8477 were achieved.