Enhancing ZnMgO Ferroelectric Properties by Defect Engineering: First-Principles and Experimental Study

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Although ZnMgO has regained attention as a ferroelectric material, the influence of defects on its ferroelectric properties remains unclear. The effects of common defects (vacancies: V O, V Zn, V Mg, and interstitials: I O, I Zn, I Mg ) on the ferroelectric properties of ZnMgO were investigated by combining first-principles with magnetron sputtering along with their formation energies and carrier concentrations. First, V O 2+, I Zn 2+, and I Mg 2+ exhibit lower formation energies under O-poor conditions, while V Zn 2–, V Mg 2–, and I O 1+ are stabilized under O-rich conditions. Second, O-rich conditions were found to reduce the net carrier concentration. Furthermore, for defect-free ZnMgO, increased Mg content reduces the spontaneous polarization magnitude (P s ) but widens the bandgap (E g ), while the polarization reversal barrier ( E a ) drops sharply near 50 atom % Mg, suggesting a transition from nonuniform to uniform polarization reversal. Meanwhile, low-concentration defects (2.778 atom %) reduce E a, P s, and E g . This indicates that a moderate level of defects can effectively facilitate polarization reversal, while a high concentration may lead to an undesirable E g . Finally, magnetron-sputtered ZnMgO films grown under varying Ar/O 2 mixtures confirm defect evolution trends and demonstrate that O-rich conditions significantly enhance breakdown field strength (E bd ). This work provides deep insight into defect formation and ferroelectric modulation, providing essential guidance for process optimization.

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