Optical and magnetic resonance study of a-SiC x N y films obtained by magnetron sputtering

Abstract

Amorphous silicon carbonitride (a-SiCxNy) thin films deposited on the SiO2 substrates by reactive magnetron sputtering was studied by Raman and electron paramagnetic resonance (EPR) spectroscopy. Raman analysis indicates the presence of C–N, Si–N, C–C bonds in a-SiCxNy films. Three EPR signals were revealed in a-SiCxNy/SiO2. One of them with g = 2.0033 was attributed to the carbon-dangling bonds (CDB). Based on the lineshape and linewidth, the EPR signal was attributed to the unpaired electron delocalized over sp2 carbon cluster. With the increase of nitrogen (N) content, the spin density of CDB significantly increases. From the temperature dependence of the linewidth and integral intensity of the CDB EPR signal, it was concluded that the antiferromagnetic ordering occurs in spin system. The antiferromagnetic exchange constant between CDBs was found to be J = −32 K. The second EPR signal having g = 2.009 was attributed to the interface defect representing threefold-coordinated Si dangling bond, which may appear due to the formation of the oxidized Si on the film surface. The third EPR signal with g = 2.05 was tentatively attributed to the trapped holes at Si atom near Si/SiO2 interface. The N incorporation in a-SiCx/SiO2 has no effect on the spin density of both interface defects.