Ferroelectricity in ScGaN grown by molecular beam epitaxy

We report on the demonstration of ferroelectric switching behavior in MBE-grown single-crystalline Sc_xGa_1-xN films on GaN templates. The polarization switching process has been investigated by multiple electrical characterization methods including P–E/J–E loops, positive-up-negative-down (PUND) measurements, and frequency-dependent measurements. A wake-up process was detected during the first several measurement cycles. After sufficient poling, large, retainable remnant polarization in the range of 60-160 µC/cm² with coercive fields in the range of 2.0-3.0 MV/cm is measured for Sc_xGa_1-xN thin films with Sc contents of 0.31-0.41. The MBE-grown ferroelectric Sc_xGa_1-xN demonstrated in this work, together with previously reported epitaxial ferroelectric Sc_xAl_1-xN, will benefit a broad range of emerging heterostructures and applications with tunable and integrated functionality in ferroelectric, electronic, optoelectronic, photovoltaic, and photonic devices and systems.