Tuning Electrical Properties and Achieving High TCR in P-Doped a-Si_xC_1−x:H Films

In this study, the characteristics of phosphorus-doped hydrogenated amorphous silicon carbide prepared by radio-frequency glow discharge decomposition of a mixture of silane (SiH₄), methane (CH₄) and hydrogen (H₂) were investigated. Molecular vibration, surface morphology, dark electrical conductivity, and activation energy were analyzed. The gas phase composition of CH₄ was varied in the range of 0.40–0.95 relative to SiH₄, while the molar fraction of phosphine (PH₃) in the gas phase was adjusted from 2.75% to 10%. It was observed that the molar fraction of carbon (C) in the film affects its homogeneity, resulting in the formation of regions rich in silicon (Si) and amorphous silicon carbide (a-Si_xC_1−x), as well as the formation of nc-Si clusters, leading to lower surface roughness. The variation in electrical properties concerning doping and the molar fraction of carbon is consistently explained in this study.