Guido Roberto, Lu Haidong, Lomenzo Patrick D, Mikolajick Thomas, Gruverman Alexei, Schroeder Uwe
NaMLab gGmbH, Noethnizer Strasse 64a, 01187, Dresden, Germany.
Chair of Nanoelectronics, Technische Universität Dresden, Noethnizer Strasse 64, 01187, Dresden, Germany.
Adv Sci (Weinh). 2024 Apr;11(16):e2308797. doi: 10.1002/advs.202308797. Epub 2024 Feb 14.
Ferroelectric wurtzite-type aluminum scandium nitride (AlScN) presents unique properties that can enhance the performance of non-volatile memory technologies. The realization of the full potential of AlScN requires a comprehensive understanding of the mechanism of polarization reversal and domain structure dynamics involved in the ferroelectric switching process. In this work, transient current integration measurements performed by a pulse switching method are combined with domain imaging by piezoresponse force microscopy (PFM) to investigate the kinetics of domain nucleation and wall motion during polarization reversal in AlScN capacitors. In the studied electric field range (from 4.4 to 5.6 MV cm), ferroelectric switching proceeds via domain nucleation and wall movement. The currently available phenomenological models are shown to not fully capture all the details of the complex dynamics of polarization reversal in AlScN. PFM reveals a non-linear increase of both domain nucleation rate and lateral wall velocity during the switching process, as well as the dependency of the domain pattern on the polarization reversal direction. A continuously faster N- to M-polar switching upon cycling is reported and ascribed to an increasing number of M-polar nucleation sites and density of domain walls.
铁电纤锌矿型氮化铝钪（AlScN）具有独特的性能，可提高非易失性存储技术的性能。要充分发挥AlScN的潜力，需要全面了解铁电开关过程中极化反转机制和畴结构动力学。在这项工作中，通过脉冲开关方法进行的瞬态电流积分测量与压电力显微镜（PFM）的畴成像相结合，以研究AlScN电容器极化反转过程中畴成核和畴壁运动的动力学。在所研究的电场范围内（从4.4到5.6 MV/cm），铁电开关通过畴成核和畴壁运动进行。结果表明，现有的唯象模型不能完全捕捉AlScN中极化反转复杂动力学的所有细节。PFM揭示了开关过程中畴成核速率和横向畴壁速度的非线性增加，以及畴图案对极化反转方向的依赖性。报道了循环时从N极到M极切换持续加快的现象，并将其归因于M极成核位点数量和畴壁密度的增加。
