Ferroelectric N-polar ScAlN/GaN heterostructures grown by molecular beam epitaxy

We demonstrate robust ferroelectricity in single-crystalline wurtzite phase N-polar ScAlN/GaN heterostructures grown on on-axis c-plane sapphire substrates by molecular beam epitaxy. The exactly aligned crystallographic orientation among the ScAlN, GaN, and substrate has been confirmed using x-ray diffraction measurements. nearly lattice-matched Sc0.21Al0.79N/GaN heterostructure shows a highly uniform coercive field (∼4.6 MV/cm at 10 kHz) remnant polarization (∼90 μC/cm2) across whole wafer. reliability of systemically characterized retention endurance tests. Both exhibit negligible degradation over 105 switching cycles, which is best reported for ferroelectric III-nitrides. This work offers viable path fully epitaxial heterogeneous integration into III-nitride heterostructures, which, together with recent demonstration metal-polar will find important applications next-generation high-power high-frequency electronics, memory acoustic resonators filters, optoelectronics, integrated quantum photonics.