Quantitative analysis of hydrogen in chemical vapor deposited diamond films

In this investigation, diamond sheets have been deposited using chemical vapor deposition. The as-grown diamond sheets were characterized for hydrogen content using detailed infrared analysis. The deconvolution of the spectra in the three-phonon region (2700-3150 cm−1) showed a number of vibration modes corresponding to spm CHn phase of carbon. The spectra representing (100) and (111) textured diamond sheets, grown under different conditions, was compared. The (100) textured sheets contained two dominant peaks centred at 2860 cm−1 and 2930 cm−1, which correspond to the symmetric and asymmetric stretch bands of CH2 group. However, the sheet with (111) texture displayed multiple CH, CH2 and CH3 peaks on the spectra. Using a standard sample called polymethyl methacrylate with known concentration, H content associated with various modes was evaluated in the diamond sheets. IR active hydrogen in the CVD diamond sheets was also calculated by evaluating the area of the IR band. Using these measurements we suggest that the oscillator strength of the different IR modes varies depending upon the structure and H content of CVD diamond sheets.