Title :
Relaxation characteristics of Ag(Ta,Nb)O3 thin film varactors
Author :
Koh, J.-H. ; Lisauskas, A. ; Grishin, A.M.
Author_Institution :
Dept. of Condensed Matter Phys., R. Inst. of Technol., Stockholm-Kista, Sweden
fDate :
28 May-1 June 2002
Abstract :
Silver tantalate niobate, which shows excellent microwave properties, was selected for this dielectric relaxation study. 4 μm gap Au(500nm)/Cr(10nm)/Ag(Ta,Nb)O3(0.4μm) interdigital capacitors (IDC) fabricated on LaAlO3 (LAO) and Al2O3 (sapphire) substrates were used as test structures. Frequency dispersion in the range 1 kHz to 1 MHz, loss tanδ, tunability and K-factor @ 100 kV/cm and 1 MHz were about 8.4%, 5.9%, 0.0033 and 17.8 and 3.5%, 3.8%, 0.0035 and 9.9 for IDCs on LAO and sapphire, respectively. Switching the voltage in stair-case mode results in slow and weak relaxation of the capacitance: at 50 kV/cm it was less than 0.05 % for 70 sec. Relaxation of leakage current follows power law: |I(t)/I∞-1| = (t/12 s)-0.98.
Keywords :
alumina; dielectric losses; dielectric relaxation; ferroelectric capacitors; ferroelectric materials; ferroelectric thin films; lanthanum compounds; leakage currents; permittivity; silver compounds; thin film capacitors; varactors; 0.4 micron; 1 kHz to 1 MHz; 10 nm; 4 micron; 500 nm; 70 sec; Ag(Ta,Nb)O3 thin film varactors; AgTaO3NbO3; Al2O3; Au-Cr-AgTaO3NbO3; LaAlO3; capacitance; frequency dispersion; interdigital capacitors; leakage current; microwave properties; relaxation characteristics; slow relaxation; staircase mode; weak relaxation; Capacitance; Dielectric substrates; Fingers; Frequency; Gold; Permittivity; Q factor; Transistors; Varactors; Voltage;
Conference_Titel :
Applications of Ferroelectrics, 2002. ISAF 2002. Proceedings of the 13th IEEE International Symposium on
Print_ISBN :
0-7803-7414-2
DOI :
10.1109/ISAF.2002.1195862
