Transitivity of band offsets between semiconductor heterojunctions and oxide insulators

By analyzing energy barriers for electrons at interfaces of Ge, GaAs, and In_0.15Ga_0.85As with insulating high-permittivity oxides (HfO₂, ZrO₂) using the spectroscopy of internal photoemission, we found that the insertion of a nanometer-thin interlayer of a dissimilar semiconductor, i.e., Si on Ge or Ge on GaAs, has no measurable influence on the interface band alignment. This result indicates the absence of any substantial interface dipoles across the stack composed of a semiconductor heterojunction and an insulating oxide and suggests the validity of the transitivity rule previously inferred on the basis of bulk–density–of–states arguments in the case of nanometer-sized multilayer structures.