Plasma environment during hot cathode direct current discharge plasma chemical vapor deposition of diamond films

The plasma characteristics have been investigated in situ by using optical emission spectroscopy (OES) and the Langmuir probe during hot cathode direc t current discharge plasma chemical vapor deposition of diamond films. The changes of atomic H and CH radical in the ground state have been calculated quantitatively according to the results of OES and the Langmuir probe meas urement as discharge current density varied. II is shown that atomic H and CH radicals both in the ground stare and in the excited state increase with the enhancement of the discharge current density in the plasma. The electr on density and CH emission intensity increase linearly with the enhancement of discharge current densities. The generation of different carbon-contain ing radicals is related to the elevation of electron temperature. Combining the growth process of diamond films and the diagnostic results, it is show n that atomic H in the excited state may improve the diamond growth efficie ntly, and the increase of electron temperature and density plays an importa nt role in the increase of the deposition rate of diamond films.