Fast deposition of microcrystalline silicon with an expanding thermal plasma

Microcrystalline silicon has been deposited using an expanding thermal plasma. High deposition rates are achieved, which is attractive for solar cell production. A first survey of the influence of the deposition parameters on the optical, electrical and structural material properties is performed. SEM analyses show columnar growth and infrared absorption shows varying oxygen content. For some of the deposition conditions the dark and photoconductivities approximate 10-7 and 10-5 S/cm, respectively. Also the deposition plasma has been studied by means of mass spectrometry. It is concluded that the expanding thermal plasma is well suited for the deposition of microcrystalline silicon at growth rates up to 3.7 nm/s.