Two basic types of methods are presently available to prepare CNTs field emission cathode. The first one is screen printing method by using CNTs paste. The large screen cathode can be made

but it is dif-ficult to control the uniform distribution of CNTs for such method. The CVD method is the second one that is ideally suited to grow film of nanotubes on pre-coating substrates with a metallic catalyst layer

which has been reported by many authors. 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. We reported the CNTs films were directly synthesized on stainless steel substrates by MWPCVD without pre-coating of catalyst layer

and especially investigated the influence of deposition conditions on field emission from such deposited carbon nanotubes films. 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 6.7×10

3

Pa

deposition time was 10 min. Scanning electron microscopy (SEM) was used to determine the morphology of carbon nanotubes. Raman spectroscopy and XRD were 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 CNT samples as the cathode were separated from the anode by a china sheet with a suitable hole as the emission area. The gap between the anode and the cathode was 500 μm. The measurement was carried out in vacuum chamber under pressure of 6.5×10

-5

Pa. By varying deposition conditions such as gas flow rate

reactive temperature

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

4

was 8 sccm

and reactive temperature was 700

8

00℃

the field emission properties of CNTs are the best. At this condition

all CNTs are disorder growth

but are of uniform with the highest density as characterized by SEM. Turn-on field of CNTs is 0.8 V/μm

and emission sites are dense and uniform.