Preparation of boron and phosphorus-doped SiC : H films using electron cyclotron resonance chemical vapor deposition: Some effects of microwave power

Hydrogenated silicon carbide films (SiC:H) were deposited using the electro n cyclotron resonance chemical vapor deposition (ECR-CVD) technique from a mixture of methane, silane, and hydrogen. and using diborane and phosphine as doping gases, The effects of changes in the microwave power on the depos ition rate and optical band gap were investigated, and variations in the ph oto- and dark-conductivities and activation energy were studied in conjunct ion with film analysis using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, foll owed by rapid reduction at high microwave powers. The ratio of the photo- t o dark-conductivity (sigma(ph)/sigma(d)) peaked at microwave power of simil ar to 600 W. Under conditions of high microwave power, Raman scattering ana lysis showed evidence of the formation and increase in the silicon microcry stalline and diamond-like phases in the films, the former of which could ac count for the rapid increase and the latter the subsequent decrease in the conductivity. In the case of phosphorus-doped SiC:H samples, it was found t hat increase in the microwave power has the effect of enhancing the formati on of the silicon microcrystalline phase in the films which occurred in cor respondence to a rapid increase in the conductivity and reduction in the ac tivation energy. The conductivity increase stabilized in samples deposited at microwave powers exceeding 500 W probably as a result of dopant saturati on. Results from Raman scattering measurements also showed that phosphorus doping has the effect of enhancing the formation of the silicon microcrysta ls in the film whereas the presence of boron has the effect of preserving t he amorphous structure.