Cold cathode and methods for producing the same

The present invention relates to the production of highly efficient films for field-effect electron emitters, wherein said films may be used in the production of flat displays, in electronic microscopes, in microwave electronics, in light sources as well as in various other applications. This invention more precisely relates to a cold cathode that comprises a substrate having a carbon film applied thereto. The carbon film has an irregular structure consisting of carbon micro-ridges and/or micro-threads which are perpendicular to the surface of the substrate, have a size ranging typically from 0.01 to 1 microns and a distribution density of between 0.1 and 10 mum2. This invention also relates to method for producing a cold electrode, wherein said method comprises generating a DC current discharge in a mixture comprising hydrogen and a carbon-containing additive, and further depositing the carbon phase on the substrate located at the anode. This method is characterized in that the discharge is generated at a current density of between 0.15 and 0.5 A/cm2. The deposition process is carried out in a mixture containing hydrogen and vapors of ethylic alcohol or methane, under an overall pressure of between 50 and 300 Torrs and at a substrate temperature of between 600 and 900° C. The concentration of ethylic alcohol vapors ranges from 5 to 10% while that of methane vapors ranges from 15 to 30%. This invention also relates to another method for producing a cold cathode, wherein said method comprises generating a microwave discharge at an absorbed power of between 100 and 1000 W. This discharge is generated in a mixture containing gaseous carbon oxide as well as methane in an 0.8-1.2 concentration and under a pressure of between 10 and 200 Torrs, the carbon phase being further deposited on the substrate. This method is characterized in that the deposition process is carried out at a temperature on the substrate surface that ranges from 500 to 700° C.