Low-energy yield spectroscopy measurements applied to determine valence band line-up at interfaces with non-homogeneous overlayers

The technique of low-energy yield spectroscopy is applied to determine the valence band line-up at heterojunctions in which the overlayer does not cov er the substrate. It is shown that by tuning the analysis energy, the contr ibution made by electrons that traverse the surface in the uncovered region s can be suppressed from the interface spectrum obtained from low-energy yi eld spectroscopy operating in the constant-final-state mode, thus allowing the determination of the band line-up without ambiguity. The method was app lied to the c-Si/c-SiC heterostructure. A value of Delta E-V = 0.78 +/- 0.0 6 eV was found for the valence band discontinuity.