UV absorption and luminescence in silicon oxynitride prepared by hydrogen-free SPCVD-process

UV absorption and luminescence are investigated in bulk samples of silicon oxynitride prepared by a hydrogen-free SPCVD-process (surface plasma chemical vapour deposition). The UV absorption spectra, apart from the well-known silicon oxygen-deficient centre (Si-ODC), exhibit two unknown absorption bands with maxima at 5.77 and 4.54 eV and two unknown luminescence bands at 3.55 and 3.03 eV under laser excitation at 257 nm (4.83 eV). These new bands are supposed to be due to a nitrogen-modified silicon oxygen-deficient centre.