Some effects of phosphorus doping in SiC:H films prepared using ECR-CVD

This paper reports the deposition of hydrogenated silicon carbide (SiC:H) films using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique. Using this technique, SiC:H films were prepared from a mixture of methane, silane and hydrogen, with phosphine as the doping gas. The effects of changing the phosphine fraction on the optical bandgap, activation energy and conductivity were investigated in films deposited at two different microwave powers of 150 and 600 W, respectively. The results showed that the deposition conditions strongly influence the structural, optical and electrical properties of the SiC:H films. In films deposited at low and high microwave powers, phosphorus doping has the effect of enhancing the formation of the silicon microcrystalline phase. In films which contain a strong silicon microcrystalline phase, the optical bandgap remained relatively constant while the conductivity increased rapidly followed by saturation. Correspondingly, the activation energy decreased and saturated suggesting an effect due to dopant saturation. The results showed that good phosphorus doping efficiency can be obtained in SiC:H films deposited at high microwave power.