CNX-LAYERS PREPARED BY PLASMA-ASSISTED CHEMICAL-VAPOR-DEPOSITION

CNx-layers were prepared by plasma assisted chemical vapour deposition methods (PACVD) with capacitively or inductively coupled plasma using different carbon precursors (CO, C2H2, CH4, C-2(CN)(4), fullerene). T he composition, structure and chemical bonds depend highly on precurso r and deposition conditions. The layers were predominantly amorphous. With CO as precursor the N/C ratio in the layers was close to that of C3N4. Small crystallites have been found in some layers by transmissio n electron microscopy, the electron microdiffraction patterns fitted t o those predicted for the beta-C3N4 and for a rhombohedral C3N4 phase. First experiments with fullerenes as carbon precursor resulted in lay ers with a N/C ratio up to 0.9. The carbon was mainly sp(3) hybridized . With hydrogen containing precursors NC ratios up to 0.9 have been me asured at temperatures below 600 K. The hydrogen content was high. Hig her temperatures led to harder layers and lower nitrogen contents. Usi ng tetracyanoethylene soft layers were obtained with a N/C ratio up to 0.7 and a high content of cyanogroups.