Breaking symmetry yields a low-loss out-of-plane tunable microwave dielectric (opens in new tab)

Voltage-tunable capacitors (varactors) are key components in microwave circuits. Tunable dielectric varactors can outperform competing technologies but typically suffer from high dielectric loss. Ruddlesden–Popper dielectric thin films can, by contrast, offer low microwave loss. Unfortunately, their crystallographic symmetry is usually not compatible with an out-of-plane parallel-plate varactor design, which can minimize size and maximize the electric field in the tunable dielectric compared ...