Bias dependent band alignment in GaO ferroelectric interface by operando HAXPES.

We present a fundamental study of the band alignment at the interface of HfZrO (HZO) with Ge-doped GaO. Ge is an alternative n-type dopant for the wide band gap GaO due to its shallow donor level and favorable MBE growth conditions. In the perspective of using the ferroelectric polarization of hafnia based oxides, we have used a stack of HZO on highly Ge doped GaO, the latter providing high carrier density.