2023/08/28 by Naseem Ud Din, Cheng‐Wei Lee, Din, Naseem Ud +5 · 2 citations
Engineering · Physics and Astronomy · #Acoustic Wave Resonator Technologies #FOS: Physical sciences #GaN-based semiconductor devices and materials #Materials Science (cond-mat.mtrl-sci) #Semiconductor materials and devices
paper · pdf · doi:10.48550/arxiv.2308.14310
openalex publication_date 2023/08/28 · openalex created_date 2023/08/31 · openalex updated_date 2026/07/28
III-nitrides and related alloys are widely used for optoelectronics and as acoustic resonators. Ferroelectric wurtzite nitrides are of particular interest because of their potential for direct integration with Si and wide bandgap semiconductors, and unique polarization switching characteristics; such interest has taken off since the first report of ferroelectric Al1-xScxN alloys. However, the coercive fields needed to switch polarization are on the order of MV/cm, which is 1-2 orders of magnitude larger than oxide perovskite ferroelectrics. Atomic-scale point defects are known to impact the dielectric properties, including breakdown fields and leakage currents, as well as ferroelectric switching. However, very little is known about the native defects and impurities in Al1-xScxN, and their effect on the dielectric properties. In this study, we use first-principles calculations to determine the formation energetics of native defects and unintentional oxygen incorporation in Al1-xScxN. We find that nitrogen vacancies are the dominant native defects, and that they introduce multiple mid-gap states that can lead to premature dielectric breakdown in ferroelectrics and carrier recombination in optoelectronics. Growth under N-rich conditions will reduce the concentration of these deep defects. We also investigate unintentional oxygen incorporation on the nitrogen site and find that the substitutional defect is present in high concentrations, which can contribute to increased temperature-activated leakage currents. Our findings provide fundamental understanding of the defect physics in Al1-xScxN alloys, which is critical for future deployment of ferroelectric devices.