Low-Energy Yield Spectroscopy as a Novel Technique for Determining Band Offsets: Application to thec−Si(100)/a−Si:HHeterostructure

We present a new experimental method for determining band lineups at the semiconductor heterojunctions and apply it to the $c-\mathrm{S}\mathrm{i}\left(100\right)/a-\mathrm{S}\mathrm{i}:\mathrm{H}$ heterostructure. This method uses a modern version of an old spectroscopy: the photoelectric yield spectroscopy excited with photons in the near UV range. It is shown that both substrate and overlayer valence-band tops can be identified in the yield spectrum due to the high escape depth and the high dynamical range of the technique, thus allowing a direct and precise determination of the band lineup. A value of $\Delta E_V=0.44\mathrm{}\pm 0.02\mathrm{eV}$ was found for the valence band discontinuity.