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◆ Ceramics2025-12-03· Ferroelectricity

Point Defect Influence on Electrical Conductivity of Semiconducting Ferroelectric AlScN

Xiaoman Zhang, Wangwang Xu, Bipin Bhattarai, Dominic A. Dalba, Dilan M. Gamachchi, Indeewari M. Karunarathne, Yue Jin Yu, Nathan J. Pravda, Ruotian Gong, David Stalla, Chong Zu, W. J. Meng, Andrew C. Meng

原始摘要(英文原文)· Original abstract
Aluminum scandium nitride (Al1−xScxN) is a promising ferroelectric material for non-volatile random-access memory devices and electromechanical sensors. However, adverse effects on polarization from electrical leakage are a significant concern for this material. We observed that the electrical conductivity of Al1−xScxN thin films grown on epitaxial TiN(111) buffered Si(111) follows an Arrhenius-type behavior versus the growth temperature, suggesting that point defect incorporation during growth influences the electronic properties of the film. Photoluminescence intensity shows an inverse correlation with growth temperature, which is consistent with increased non-radiative recombination from point defects. Further characterization using secondary ion mass spectrometry in a focused ion beam/scanning electron microscope shows a correlation between trace Ti concentrations in Al1−xScxN films and the growth temperature, further suggesting that extrinsic dopants or alloying components potentially contribute to the point defect chemistry to influence electrical transport. Investigation of the enthalpy of formation of nitrogen vacancies in Al1−xScxN using density functional theory yields values that are in line with electrical conductivity measurements. Additionally, the dependence of nitrogen-vacancy formation energy on proximity to Sc atoms suggests that variations in the local structure may contribute to the occurrence of point defects, which, in turn, can impact electrical leakage. Furthermore, we have demonstrated ferroelectric behavior through electrical measurements and piezoresponse force microscopy after dc bias poling of films in spite of electrical conductivity spanning several orders of magnitude. Although electrical leakage remains a challenge in Al1−xScxN, the material holds potential due to tunable electrical conductivity as a semiconducting ferroelectric material.
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Point Defect Influence on Electrical Conductivity of Semiconducting Ferroelectric AlScN — 科研速览 Science Skim