Comparative study of trap-limited hydrogen diffusion in amorphous SiC, Si0.66C0.33N1.33, and SiN1.33 films

Hydrogen tracer diffusion is studied in amorphous SiC, Si0.66C0.33N1.33, and SiN1.33 films which were produced by rf magnetron reactive sputtering and which contain about 0.5 at.% of hydrogen. The diffusion experiments were carried out in the temperature range between 700 and 1000 degrees C with ion-implanted deuterium tracer isotopes and secondary ion mass spectrometry. Effective diffusivities are derived which are nearly identical for all three types of material and which obey Arrhenius behaviours with activation energies of Delta E = 3.0-3.4 eV and pre-exponential factors of the order of D-0 = 10(-4)-10(-5) m(2) s(-1). These results can be explained with a trap-limited diffusion mechanism of hydrogen where the tracer atoms are temporarily trapped by carbon and nitrogen dangling bonds, which have approximately the same binding energy to hydrogen.