Electron field emission studies from amorphous carbon thin films

One of the largest potential applications for amorphous carbon (a-C) thin films is in electron field emitting devices. We have deposited hydrogenated a-C (a-C:H) thin films on silicon substrates as a function of self-bias and pressure using a standard capacitively coupled RF PECVD system. Emission of electrons is observed at threshold fields as low as 6 V mu m(-1) after conditioning. The threshold held at which the electron emission takes place does not seem to vary in a systematic manner as a function of self-bias but shows a minimum threshold for the a-C:H film with the highest sp(3) content. We have explained the electron emission that occurs in these films as being due to a space charge effects caused by band bending in the films, with the a-C:H film acting as a space charge interlayer with the true cathode being the silicon. We have also conducted lifetime tests. Following our previous work on nitrogen-doped a-C:H films [1], we report the characteristics observed for undoped a-C films. (C) 1998 Elsevier Science S.A.