New insights on growth mechanism of a‐Si:H from optical emission spectroscopy

Optical emission spectra from the silane plasma have been measured as a function of silane flow rate. The relative concentrations of the emissive species, SiH (414 nm), Si (288 nm), and H (656 nm), have been determined. The growth rate and vibrational spectra of the resulting films are interpreted in terms of the emission intensities of the SiH and H radicals, and the diffusional mass transport of these neutral radicals is suggested to be responsible for the deposition process of a‐Si:H. From the optical emission spectroscopy of doping gases, decompostion rate of diborane is found to be much less than that of phosphine. Extremely high doping efficiencies of boron and phosphorus atoms have been realized by lowering the emission intensity of the SiH band with respect ot the H₂ line.