Field emission characterization of carbon nanostructures for cold cathode applications

Local (/spl sim//spl mu/m/sup 2/) field emission (FE) properties of nanocrystalline diamond (ND) with considerable non-diamond content and of carbon nanotubes (CNT) were investigated by means of a FE scanning microscope. This setup combines high resolution (/spl ap/ 100 nm) FE measurements with in situ surface analysis (e.g. scanning electron microscopy). The samples were fabricated by bias treatment in a CVD setup. Measurement of the onset field strength E/sub on/, and current carrying ability and processing effects revealed for both materials the potential for cold cathode applications. The ND with an E/sub on/=E(0.5 nA) between 55 V//spl mu/m and 79 V//spl mu/m showed stable Fowler Nordheim (FN) like emission up to 1.2 /spl mu/A (/spl Delta/_107 mA/cm/sup 2/) and 8.7 /spl mu/A (/spl Delta/_777 mA/cm/sup 2/) before and after current processing at 9 /spl mu/A, respectively. For the CNT the electron emission started at 8.6 V//spl mu/m with FN like behavior up to 30 nA/9 /spl mu/m/sup 2/. While emissivity and stability of the ND was enhanced by the current processing, a FE degradation of the CNT was observed at very high (/spl les/21 /spl mu/A through 9 /spl mu/m/sup 2/) current levels.