A General Strategy to Achieve Colossal Permittivity and Low Dielectric Loss Through Constructing Insulator/Semiconductor/Insulator Multilayer Structures

In this work, we propose a route to realize high-performance colossal permittivity (CP) by creating multilayer structures of insulator/semiconductor/insulator. To prove the new concept, we made heavily reduced rutile TiO₂ via annealing route in Ar/H₂ atmosphere. Dielectric studies show that the maximum dielectric permittivity (~ 3.0 × 10⁴) of our prepared samples is about 100 times higher than that (~ 300) of conventional TiO₂. The minimum dielectric loss is 0.03 (at 10⁴–10⁵ Hz). Furthermore, CP is almost independent of the frequency (100–10⁶ Hz) and the temperature (20–350 K). We suggest that the colossal permittivity is attributed to the high carrier concentration of the inner TiO₂ semiconductor, while the low dielectric loss is due to the presentation of the insulator layer on the surface of TiO₂. The method proposed here can be expanded to other material systems, such as semiconductor Si sandwiched by top and bottom insulator layers of Ga₂O₃.