Preparation of nitrogen-rich CNx films with inductively coupled plasma CVD and pulsed laser deposition

Nitrogen-rich amorphous carbon nitride films with N/(N + C) greater than or equal to 0.5 have been deposited with three different methods, namely: (i) inductively coupled plasma CVD utilizing chemical transport reactions (ICP-CTR); (ii) inductively coupled plasma CVD with gaseous precursors (ICP-GP) and (iii) pulsed laser deposition (PLD) with additional r.f. plasma discharge. By means of plasma diagnostic measurements it is shown that in each case high concentrations of active radical species (e.g. CN* and N*) are necessary to obtain high nitrogen concentrations. On the other hand, these nitrogen-rich films turned out to be mainly sp(2) bonded having rather low densities of 1.8-2.0 g cm(-3) only, irrespective of the method. From a comparison of the three techniques, and of further literature data, conclusions are drawn regarding the conditions necessary to obtain high N/(N + C) ratios, and regarding the deposition of superhard, crystalline Sp(3) bonded carbon nitride modifications. (C) 2001 Elsevier Science B.V. All rights reserved.