Crystallization of phosphorus-doped a-Si:H has been initiated at a substrate temperature below 200 °C, under the deposition conditions of a low flow rate of silane and in the presence of an external magnetic field. Along with the crystallization, the doping efficiency of the resulting Si:H films has been remarkably improved. Room-temperature conductivity as high as 27 Ω−1 cm−1 has been achieved at a doping ratio of NPH3/NSiH4=5.6×10−3 for a specimen deposited at 30 C. Optical emission spectroscopy during the plasma deposition has revealed that a weak emission intensity of the SiH band with respect to hydrogen lines and the absence of emission from the doubly excited states of hydrogen molecules are necessary conditions for the crystallization of doped Si:H films.

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We have measured the optical-emission spectra of the silane plasma as a function of the external magnetic field, together with the growth rate and vibrational spectra of the resulting a-Si:H films. The optical-emission intensities of the reactive species SiH, H2, and H produced in the plasma are appreciably affected by the magnetic field, and the corresponding change in the hydrogen bonding of the deposited films is interpreted in terms of chemical reaction among the species.