Influence of oxygen pressure during deposition on the microwave dielectric tunability of Ba0.5Sr0.5TiO3 thin films in PLD process

• Published in: Applied surface science 2024-10, Vol.669, p.160477, Article 160477
• Main Authors: Akhil Raman, T.S., Arun, B., Shivakumar, C., Joseph, Andrews, James Raju, K.C.
• Format: Article
• Language: English
• Subjects: BST; Oxygen pressure; PLD; Thin films; Tunability
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2024.160477

[Display omitted] •BST thin films prepared at different oxygen partial pressures using PLD.•Microwave dielectric properties were estimated by fabricating a CPC structure and measured using on-wafer probing technique.•High microwave dielectric tunability was observed in the BST films deposited at higher oxygen pressure. Thin films of Ba0.5Sr0.5TiO3 (BSTO) were pulsed laser deposited on platinized silicon substrates with varying oxygen pressure from 5 × 10−1 mbar to 5 × 10−6 mbar. A strong correlation between the oxygen partial pressure during the PLD process and the structural and microwave dielectric properties of the PLD-grown BSTO thin films is observed. The structural properties of the PLD-grown BSTO films were analyzed by XRD, Raman spectroscopy, FTIR spectroscopy, and XPS studies, and it is observed that oxygen vacancies are formed in low oxygen pressure deposited films. Dielectric studies at microwave frequencies show that high oxygen pressure deposited BSTO films show good microwave dielectric properties and crystallinity. At 1 GHz frequency, the BSTO film grown at 5 × 10−2 mbar oxygen pressure exhibits a dielectric constant ∼470 and dielectric loss ∼0.15. The oxygen vacancies change the nature of metal-oxide bonding (Ti-O bond), affect the polarizabilities, and, as a result, reduce the dielectric constant. A maximum dielectric tunability of 71 % is observed in microwave frequencies for the BSTO films grown at 5 × 10−2 mbar oxygen pressure.