Composition-control of magnetron-sputter-deposited (Ba{sub x}Sr{sub 1-x})Ti{sub 1+y}O{sub 3+z} thin films for voltage tunable devices
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Energy Technology Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Materials Science and Chemistry Divisions, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Precise control of composition and microstructure is critical for the production of (Ba{sub x}Sr{sub 1-x})Ti{sub 1+y}O{sub 3+z} (BST) dielectric thin films with the large dependence of permittivity on electric field, low losses, and high electrical breakdown fields that are required for successful integration of BST into tunable high-frequency devices. Here, we present results on composition-microstructure-electrical property relationships for polycrystalline BST films produced by magnetron-sputter deposition, that are appropriate for microwave and millimeter-wave applications such as varactors and frequency triplers. Films with controlled compositions were grown from a stoichiometric Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} target by control of the background processing gas pressure. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O{sub 2}) process pressure, while the O{sub 2}/Ar ratio did not strongly affect the metal ion composition. Film crystalline structure and dielectric properties as a function of the (Ba+Sr)/Ti ratio are discussed. Optimized BST films yielded capacitors with low dielectric losses (0.0047), among the best reported for sputtered BST, while still maintaining tunabilities suitable for device applications. (c) 2000 American Institute of Physics.
- OSTI ID:
- 20215173
- Journal Information:
- Applied Physics Letters, Vol. 76, Issue 5; Other Information: PBD: 31 Jan 2000; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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