Linearity and temperature dependence of large area processed high Q BST varactors
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Ba0.6Sr0.4TiO3 (BST) thin-films with large dielectric tunability as high as 4:1 were obtained using a large-area pulsed laser deposition process, with low loss-tangents below 0.01 at zero-bias and 10 GHz. This paper summarizes experimental results obtained on large-area processed BST thin films on 100-mm-diameter sapphire substrates characterized using a varactor shunt switch test structure. Varactors with 0.25-μm-thick BST films exhibited large dielectric tunability, the relative dielectric permittivity at zero bias of 990 tuned to 250 at an electric field of 320 kV/cm. The leakage current through the BST film was below 2 nA up to 6 V dc bias. The quality factor (Q) exceeded 300 at relatively low 6 V dc bias for the BST varactors at 1 GHz. These results confirm that large-area processed BST thin films are ready to compete with semiconductor varactors for commercial applications at RF, microwave, and millimeterwave frequencies.
1692 - 1695
Copyright © 2010, IEEE
barium compounds;dielectric losses;leakage currents;permittivity;pulsed laser deposition;strontium compounds;thin film capacitors;varactors;Al2O3;BST thin-films;BST varactors;Ba0.6Sr0.4TiO3;dielectric tunability;frequency 1 GHz;frequency 10 GHz;high-Q barium strontium titanate thin-film varactors;leakage current;loss-tangents;pulsed laser deposition process;relative dielectric permittivity;sapphire substrates;semiconductor varactors;size 0.25 mum;size 100 mm;varactor shunt switch test structure;zero-bias;Barium;Binary search trees;Dielectric substrates;Dielectric thin films;Linearity;Strontium;Temperature dependence;Titanium compounds;Transistors;Varactors
Subramanyam, Guru; Patterson, M.; Leedy, K.; Neidhard, R.; Varanasi, C.; Zhang, C.; and Steinhauer, G., "Linearity and temperature dependence of large area processed high Q BST varactors" (2010). Electrical and Computer Engineering Faculty Publications. 23.