Annealing reduces leakage current in MBE grown AlScN and AlYN films

Ternary aluminum scandium nitride (AlScN) and aluminum yttrium nitride (AlYN) are emerging wide-bandgappiezoelectric and ferroelectric materials with significant potential for next-generation electronic devices. This workinvestigates the impact of post-growth annealing on the structural, electrical, and piezoelectric properties of AlScN andAlYN thin films grown by plasma-assisted molecular beam epitaxy (MBE). Annealing is performed in vacuum, air, andnitrogen atmospheres at temperatures ranging from 750 {degree sign}C to 1100 {degree sign}C . It is observed that annealing in air and nitrogenlowers the leakage current in AlScN and AlYN films. Piezoelectric coefficient (d33) enhancements as high as 139 pm/Vfor AlScN and 157 pm/V for AlYN are observed, notably for vacuum-annealed samples at 900 {degree sign}C. Preservation offerroelectric switching properties post-annealing is confirmed by piezo-response force microscopy (PFM) and PUNDmeasurements. These findings highlight the role of thermal treatments on the performance of AlScN and AlYN forpiezoelectric, ferroelectric, and high-K dielectric device applications.