Band alignment and polarization engineering in κ-Ga2O3/GaN ferroelectric heterojunction

Ferroelectric-semiconductor heterostructures offer an alternative strategy to manipulate polarization towards advanced devices with engineered functionality and improved performance.In this work,we report on the heteroepitaxial construction,band structure alignment and polarization engineering of the single-phasedκ-GaO/GaN ferroelectric/polar heterojunction.A type-II band alignment is determined at theκ-GaO/GaN polar hetero-interface,with a valence band offset of (1.74±0.1) eV and a conduction band offset of (0.29■0.1) eV.Besides the band edge discontinuity,charge dipoles induced by spontaneous polarization lead to the observed band bending with built-in potentials of 0.9 and 0.33 eV,respectively,at theκ-GaOsurface andκ-GaO/GaN interface.The polarization switching properties of ferroelectricκ-GaOare identified with a remanent polarization of approximately 2.7μC/cm~2 via the direct hysteresis remanent polarization/voltage (P-V) loop measurement.These findings allow the rational design ofκ-GaOferroelectric/polar heterojunction for the application of power electronic devices,advanced memories and even ultra-low loss negative capacitance transistors.