In situ determination of dielectric functions and optical gap of ultrathin amorphous silicon by real time spectroscopic ellipsometry

Abstract

We have developed techniques to determine the near‐infrared to near‐ultraviolet dielectric function and optical gap of ultrathin amorphous silicon [a‐Si:(H)] using real‐time spectroscopic ellipsometry during preparation and processing. The techniques have been applied to ∼50 Å a‐Si:H films prepared by plasma‐enhanced chemical vapor deposition, and to ∼250 Å pure a‐Si chemically modified by atomic H exposure. For the latter, the time evolution of the bonded H content can be estimated along with the evolution of the gap.