Study of the stress in doped CVD diamond films

Sulphur-doped and boron-sulphur co-doped diamond thin films were prepared using chemical vapour deposition (CVD) on Si substrates under different conditions. The influence of doping on stress in CVD diamond films were investigated with X-ray diffraction and Raman spectra. The results show that the sp2-carbon content, the concentration of defects and the residual compressive stress in CVD diamond films increase with increasing of sulphur content. Compared with sulphur doping of diamond films, the boron-sulphur co-doping with few boron atoms facilitates sulphur atom incorporation into diamond crystal. The boron-sulphur complexes in diamond can reduce crystal lattice distortion and crystal imperfection. As a result, sp2-carbon content and residual compressive stress in boron-sulphur co-doped diamond are reduced, and diamond crystal prefection is improved.