화학공학소재연구정보센터
Applied Surface Science, Vol.184, No.1-4, 268-272, 2001
Comparative EPR study of hydrogenated and unhydrogenated amorphous silicon carbide thin films
In this work, electron paramagnetic resonance (EPR) is used to study paramagnetic centers in stoichiometric hydrogenated a-SiC:H synthesized by plasma enhanced chemical vapor deposition (PECVD) and unhydrogenated a-SiC grown by pulsed laser deposition. While the spin density of the a-SiC films was determined to be: of the order of 10(20) spins/cm(3), it was found to be more than one order of magnitude lower (10(19) spins/cm(3)) for the as-deposited a-SiC:H films and decreases to less than 10(17) spins/cm(3) upon annealing at 650 degreesC. For both types of films, the dominant paramagnetic centers in the films are carbon related defects, as deduced from the g-value of the EPR signal. The PLD a-SiC films have a symmetric exchange narrowed Lorentzian EPR line that indicates some clustering of the spins. For a-SiC:H films, the EPR shows some asymmetry that is probably due to the presence of silicon related defects in the layers. No evidence of spin clustering was found for a-SiC:H and the EPR linewidth is most likely determined by dipolar interaction and some unresolved hydrogen hyperfine structure for the as-deposited and annealed a-SiC:H films, respectively. The temperature dependence of the EPR linewidth for both types of films and the power saturation behavior of the EPR signal are also presented and discussed.