Dielectric Properties of Ba _0.7 Sr _0.3 TiO ₃ Film at Terahertz Measured by Metamaterials

Abstract

A metamaterial device with resonance frequency at THz was reported in this article. The device was composed of split‐ring resonators ( SRR ), ferroelectric Ba 0.7 Sr 0.3 TiO 3 ( BST 70) film, and alumina substrates. The SRR of 140 nm thick Au/Ti was fabricated on BST 70 film with periodicity of 50 μm, width of 10 μm, and gap of 8 μm. The BST 70 thin film was deposited on alumina substrates using a sol–gel technique. Terahertz time domain spectroscopy was used to characterize electromagnetic response of the metamaterial at various temperatures. Finite difference time domain was used to simulate the transmission spectra of the metamaterial at THz frequencies. Dielectric constant of the BST 70 film at THz, in the temperature range from 0°C to 100°C, was derived by comparing the simulated resonance frequency with the experimental curves.