Spectroscopic studies of hydrogen related defects in CVD diamond

Thin diamond films prepared by the hot filament chemical vapour deposition (HFCVD) method at various deposition pressures have been characterized usin g a variety of spectroscopic techniques. Interpretation of the spectral det ails have provided useful information about the nature of the films. Deposi tion pressure appears to affect the quality of the diamond films which is r eflected in terms of the position and width of the characteristic Raman pea k of diamond. Raman spectra of the films prepared at low deposition pressur es showed the presence of a sharp peak at similar to 1332 cm(-1) characteri stic of the T-2g mode of diamond. The study of the effect of deposition pre ssure on the diamond growth, shows that in the range between 20 torr and 60 torr, there is little effect on the width and the shift of the 1332 cm(-1) Raman peak. However, at higher pressures the peak showed a blue shift and was considerably broadened. These studies indicate the development of strai n in the lattice due to the introduction of unetched hydride layer, at high er deposition pressures, as well as distortions in the lattice leading to p artial lifting of the degeneracy of the T-2g mode. A broad band correspondi ng to the non-diamond phase (which exists at the grain boundaries, interfac e or as inclusions inside the grain), which can be attributed to the effect of hydrogen impurity creeping into the lattice at higher deposition pressu res is also observed. SEM and XRD patterns have confirmed the dominance of diamond phase in these films.