Silicon-integrated lead-free BaTiO3-based film capacitors with excellent energy storage performance and highly stable irradiation resistance

Abstract

Silicon integrated lead-free oxide thin film capacitors with high energy storage density (W_re), high efficiency (η) and good thermal stability have great application potential in modern communication fields. Here, 1 mol% SiO₂-doped Ba(Zr_0.35Ti_0.65)O₃ (BZTS) thin film capacitors are integrated on Si and HfO₂ buffered Si substrates by using a radio-frequency magnetron sputtering system. It is found that the energy storage performances are significantly improved by inserting an HfO₂ buffer layer (about 13.5 nm) between the BZTS layer and the Si substrate. The improved W_re of the BZTS/HfO₂ thin film capacitors can be up to 93.48 J cm⁻³ at room temperature, which is about 65% higher than that of the film without the HfO₂ buffer layer, and the η is ∼ 71.44%. Moreover, the introduction of the HfO₂ buffer layer leads to a superior thermal stability in a wide temperature range from −100 °C to 200 °C with a very small change rate of ∼3.39%. Under different irradiations with doses of He⁺ from 1 × 10¹² ions per cm² to 7 × 10¹⁵ ions per cm² and neutrons from 5 × 10¹² ions per cm² to 1 × 10¹⁴ ions per cm², the BZTS thin film capacitors with the HfO₂ buffer layer show ultra-stable energy storage performance. Our research provides an effective strategy for the integration of high performance BZTS thin film capacitors on Si substrates, and our results demonstrate potential of the Si integrated thin film capacitors for the application in nuclear technology, space stations, satellites, radiation centers and other harsh environments.