Dielectric Properties of Ba0.7Sr0.3TiO3 Film at Terahertz Measured by Metamaterials

A metamaterial device with resonance frequency at THz was reported in this article. The device was composed of split-ring resonators (SRR), ferroelectric Ba0.7Sr0.3TiO3 (BST70) film, and alumina substrates. The SRR of 140 nm thick Au/Ti was fabricated on BST70 film with periodicity of 50 mu m, width of 10 mu m, and gap of 8 mu m. The BST70 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 BST70 film at THz, in the temperature range from 0 degrees C to 100 degrees C, was derived by comparing the simulated resonance frequency with the experimental curves.