The preparation and characteristics of silicon nanoarrays is now an attractive areas of research. At present

most research focused on the optical and electrical properties and applications

and less field emission characteristics

as a mature technology of silicon planar support

silicon field emission cathode materials are easily compatible with the microelectronic integrated circuits

and so they have a broad application prospects.We present the fabrication of large-scale two dimensional periodic silicon nanoarrays using nanosphere lithography

and the field emission characteristics have been studied. The fabrication process includes following steps: first the crystalline silicon substrate was coated with a monolayer of self polystyrene (PS) spheres of 220 nm in diameter

then the sample was etched by reactive ion etching to produce silicon nanoarrays. AFM images of the nanoarrays show that the tips stand 60～70 nm high and the area density can achieve 6×10

9

/cm

2

. All field emission measurements were performed at a vacuum of 1.0×10

-4

Pa or better. Expected to improve the field emission characteristics

about 60 nm thickness of a amorphous carbon film was deposited on top of the silicon nanoarrays by plasma-enhanced chemical vapour deposition. Field emission results show that compared to silicon nanoarrays

silicon nanoarrays coated with a thin a-C film effectively lower the threshold fields

approximately 8.1 V/μm

while field enhancement factor increased. When the electric field intensity reached 20 V/μm

the current density can reach about 1.4 mA/cm

2

. The improvement of field emission originates from the anisotropic structure of the films

when conductive sp

2

clusters embedded in an insulating sp

3

matrix

the electric field has been enhanced.