Effect of initial-annealing on thermal stability of hydrogen in C-SiC:H films

The samples of carbon-rich silicon carbide (C-SiC) films were prepared by using ion beam mixing. Some were initial-annealed at 673 K in vacuum and the others were untreated for comparison. After that, all samples were irradiated by 5 keV hydrogen ion beam and isothermally post-annealed at the temperature from 473 to 873 K. Depth distributions of hydrogen obtained by secondary ion mass spectrometry (SIMS) show that the volume of hydrogen released from C-SiC:H films without initial-annealing is more than the one with initial-annealing at the temperature from 573 to 873 K. Further Fourier transform infrared (FTIR) measurements reveal that the integrated intensities of Si-H stretching vibration peaks remarkably reduced at the temperature from about 500 to 700 K and became stable beyond 800 K, and the ones of C-H stretching vibration peaks were almost uniform below 800 K. The ratios of Si-H to C-H integrated intensities for the C-SiC:H films with initial-annealing are larger than the ones without initial-annealing during post-annealing. This shows that the ratio of Si-H to C-H bonds increased due to initial-annealing, which means that initial-annealing could result in the decline of thermal stability of hydrogen in C-SiC:H films at the temperature from about 500 to 700 K.