Role of film stoichiometry and interface quality in the performance of (Ba,Sr)TiO3 tunable capacitors with high figures of merit
Abstract
Parallel plate capacitors with quality factors exceeding 1000 were fabricated using Ba0.3Sr0.7TiO3 (BST) thin films grown by hybrid molecular beam epitaxy on epitaxial Pt bottom electrodes. The influence of film stoichiometry was investigated by varying the (Ba + Sr)/Ti ratio around the stoichiometric composition. The quality factor is highest for stoichiometric films, but (Ba + Sr)-rich films can be biased to higher fields. Furthermore, two different processes were used to deposit the top electrodes of the parallel plate capacitors. While the quality of the top contact/BST interface did not strongly affect the device quality factor, an enhancement in the dielectric tunability was seen for capacitors with top electrodes deposited at high temperatures, which effectively removes interfacial contamination layers.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 07, 2016
- Source ID
- 10.1063/1.4967374
Entities
People
- Christopher R. Freeze
- Susanne Stemmer
Organizations
- Army Research Office
- National Science Foundation
- University of California