In situ - gas phase analysis during silicon thin film deposition: molecular beam sampling, laser ionisation and mass spectrometry

摘要

Si atoms evaporating from an electrically heated Si wire are applied for thin film deposition on a substrate and detected in an effusive molecular beam originating from an aperture in the substrate. (1+1)-REMPI with a frequency doubled dye and a KrF laser allows to selectively detect Si atoms in their electronic ground state using a time-of-flight mass spectrometer (TOF-MS). The hot Si wire (1000 - 1500 K) is furthermore used to pyrolyse SiH_4 and deposit a-Si:H thin films. Gas sampling in the substrate (molecular beam), photoionisation with a KrF or ArF laser, and TOF-MS reveal H_2, SiH_2 and Si_2H_6 as pyrolysis products. Under the applied conditions a-Si:H thin film formation can be explained with SiH_2 acting as film forming species.