Phase-pure antiferroelectric AgNbO3 films on Si substrates: chemical solution deposition and phase transitions

Abstract

AgNbO₃-based antiferroelectric films have attracted emerging attention in the field of dielectric energy storage and possess promising applications in photocatalysis and microwave devices. Unfortunately, it remains a challenge to fabricate pure-phase AgNbO₃ films on Si substrates, precluding their further integration into electronic devices. Here, we, for the first time, report phase-pure AgNbO₃ films on Pt/Ti/SiO₂/Si substrates by a chemical solution deposition (CSD) method. A facile CSD route without using the hazardous pyridine additive is demonstrated to obtain a stable AgNbO₃ precursor for spin-coating films. By comprehensively controlling the heat treatment conditions, secondary phases are eliminated in the deposited films. The phase transitions of the AgNbO₃ films are also investigated, where intriguingly the room temperature phase is determined to be the antiferroelectric M₂ phase, rather than the commonly reported M₁ phase in bulk AgNbO₃. Meanwhile, the relative dielectric permittivity surpasses 300 at room temperature and maintains at ∼400 with low dielectric loss (<0.05; measured at frequencies of 0.1–1 MHz) over a wide temperature range of 150–350 °C, within a 5% variation. This work provides an easy-to-implement process of AgNbO₃ films which may attract scientific interests and potential applications.