Oxygen Doping in Ferroelectric Wurtzite‐type Al0.73Sc0.27N: Improved Leakage and Polarity Control

This study examines systematic oxygen (O)-incorporation to reduce totalleakage currents in sputtered wurtzite-type ferroelectric Al0.73Sc0.27N thin films,along with its impact on the material structure and the polarity of the as-grownfilms. The O in the bulk Al0.73Sc0.27N was introduced through an external gassource during the reactive sputter process. In comparison to samples withoutdoping, O-doped films showed almost a fourfold reduction of the overall leak-age current near the coercive field. In addition, doping resulted in the reductionof the steady-state leakage currents by roughly one order of magnitude at sub-coercive fields. The microstructure analysis through X-ray diffraction (XRD)and scanning transmission electron microscopy (STEM) indicated no notablestructural degradation in the bulk Al0.73Sc0.27N. The maximum O-doped filmexhibited a c-axis out-of-plane texture increase of only 20%, rising from 1.8°,while chemical mapping indicated a consistent distribution of O throughoutthe bulk. Our results further demonstrate the ability to control the as-depositedpolarity of Al0.73Sc0.27N via the O-concentration, changing from nitrogen(N)- to metal (M)-polar orientation. Thus, this article presents a promisingapproach to mitigate the leakage current in wurtzite-type Al0.73Sc0.27N withoutincurring any significant structural degradation of the bulk thin film, therebymaking ferroelectric nitrides more suitable for microelectronic applications.

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