High-tunability and low-microwave-loss Ba0.6Sr 0.4TiO3 thin films grown on high-resistivity Si substrates using TiO2 buffer layers

Hyun Suk Kim, Ho Gi Kim, Il Doo Kim, Ki Byoung Kim, Jong Chul Lee

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

In this Letter, we report on high-tunability and low-microwave-loss properties of Ba0.6 Sr0.4 TiO3 (BST) thin films by use of atomic-layer-deposited TiO2 films as the microwave buffer layer between BST and high-resistivity Si substrate. The interdigital capacitor fabricated on BST films grown on TiO2 high resistivity Si (2 kΩ cm) substrates showed the much enhanced tunability value of 33.2% while retaining an appropriate Q factor, as compared to the tunability values of BST (21%) films grown on MgO single-crystal substrates and BST (8.2%) films grown on TiO2 normal Si (10 Ω cm) substrates. The coplanar waveguide BST phase shifter fabricated on TiO2 high resistivity Si exhibited a phase shift of 95° and insertion loss of 3.09 dB at 15 GHz and an applied voltage of 50 V. ALD-grown TiO2 buffer layers enable the successful integration of BST-based microwave tunable devices onto high-resistivity Si wafers.

Original languageEnglish
Article number212903
Pages (from-to)1-3
Number of pages3
JournalApplied Physics Letters
Volume87
Issue number21
DOIs
StatePublished - 2005

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