Dielectric Spectroscopy of PLD-Grown BST Thin Films across the Electromagnetic Spectrum

Dielectric properties of ferroelectric materials are fundamental to understanding a range of phenomena in electronics, optics, and solid-state physics. Due to the frequency-dependent nature of their dielectric response, these materials find extensive use across multiple frequency domains. In the present study, a comprehensive investigation has been carried out on the dielectric behavior of barium strontium titanate (Ba1–xSrxTiO3) thin films with compositions x = 0.2 and 0.5, across a wide frequency spectrum spanning from kilohertz (kHz) to terahertz (THz) regimes. Pulsed laser deposition (PLD) has been employed for the deposition of thin films on suitable substrates under the optimized conditions. Dielectric measurements were performed in three distinct frequency ranges: low (1 kHz to 10 MHz), microwave (2 to 20 GHz), and optical (270 to 950 THz). The Ba0.8Sr0.2TiO3 thin film has a dielectric constant of 310.28 at 10 kHz, 21.12 at 10 GHz, and 2.34 at 500 THz. In comparison, the dielectric constant of the Ba0.5Sr0.5TiO3 thin film was 510.29 at 10 kHz, 20.01 at 10 GHz, and 4.40 at 500 THz. The observed variation in dielectric properties with frequency and composition emphasizes the intriguing prospect of Ba1–xSrxTiO3 thin films for tunable dielectric applications across a broad electromagnetic spectrum.