Title :
Tunable SrTiO/sub 3/ varactors using parallel plate and interdigital structures
Author :
Mueller, C.H. ; Treece, R.E. ; Rivkin, T.V. ; Miranda, F.A. ; Moutinho, H.R. ; Swartzlander-Franz, A. ; Dalberth, M. ; Rogers, C.T.
Author_Institution :
SCT, Golden, CO, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
The dielectric properties of SrTiO/sub 3/ (STO)/YBCO and STO films deposited on LaAlO/sub 3/ substrates were evaluated, for potential varactor applications wherein the capacitance is altered via a dc voltage applied across the STO film. The optimal growth temperature for the STO films in the STO/YBCO structures was 800/spl deg/C; higher temperatures resulted in interfacial degradation and poor film quality, and lower temperatures resulted in films with lower dielectric constants (/spl epsi//sub r/) and tunabilities. Interdigital varactors comprised of STO films deposited directly on LaAlO/sub 3/ displayed higher tunabilities and significantly lower losses.
Keywords :
barium compounds; capacitance; high-temperature superconductors; lanthanum compounds; losses; permittivity; strontium compounds; superconducting junction devices; superconducting microwave devices; superconducting thin films; varactors; yttrium compounds; 800 degC; LaAlO/sub 3/; SrTiO/sub 3/-YBaCuO-LaAlO/sub 3/; capacitance; dc voltage; dielectric constants; film quality; interdigital structures; interfacial degradation; losses; optimal growth temperature; parallel plate structures; tunable varactors; Dielectric constant; Dielectric substrates; Electrodes; Gold; Superconducting films; Superconducting microwave devices; Temperature; Tunable circuits and devices; Varactors; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
