Synthesis and characterization of (Ba{sub x}Sr{sub 1-x})Ti{sub 1+y}O{sub 3+z} thin films and integration into microwave varactors and phase shifters.
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 review recent results on composition-microstructure-electrical property relationships of polycrystalline BST films produced by magnetron sputter deposition, that are appropriate for microwave devices such as phase shifters. 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 layers yielded capacitors with low dielectric losses (0.0047), among the best reported for sputtered BST, while still maintaining tunabilities suitable for device applications. These BST films were used to produce distributed-circuit phase-shifters, using a discrete periodic loading of a coplanar waveguide with integrated BST varactors on high-resistivity silicon. Phase shifters yielding 30 degrees of phase shift per dB of insertion loss were demonstrated at 20GHz.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC; EE; DOD
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 942902
- Report Number(s):
- ANL/MSD/JA-35759
- Journal Information:
- Integr. Ferroelectrics, Journal Name: Integr. Ferroelectrics Journal Issue: 1-4 ; 2001 Vol. 34; ISSN 1058-4587
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Ba{sub 1{minus}x}Sr{sub x}TiO{sub 3} thin film sputter-growth processes and electrical property relationships for high frequency devices
Magnetron sputter-deposited multilayer (Ba{sub x}Sr{sub 1x})Ti{sub 1+y}O{sub 3+z} thin films for passive and active devices.