A low-loss BST thin film on initial nucleation layer for micro and millimeter wave tunable phase shifter

Improved Ferroelectric Phase Shifter by Inserting Spiral Inductors into Ground

“…BaSrTiO 3 (BST) thin films have been investigated as a potential low cost voltage tunable element for microwave circuit applications because of their high tunability, relatively low loss, and fast switching speed [1][2][3][4][5][6][7]. At present, several groups have implemented phase shifters using BST thin films [8][9][10][11][12][13]. Typically, larger varactors must be loaded or higher voltage should be biased in order to obtain higher phase shift.…”

New Tunable Microwave Ba0.6Sr0.4TiO3/MgO Phase Shifters Using Interdigital Capacitors and Slit-Inductors

“…3,4) There have been some earlier promising results in coplanar waveguide (CPW) phase shifters with the use of BST films using interdigital capacitor (IDC) configurations on single crystal substrate such as MgO which can provide low insertion loss, good lattice match, and good mechanical support. [5][6][7] As a potential approach for enhancing phase shifting performance, we have recently developed phase shifters using narrow transverse slits which can offer an increase in the amount of induced inductance. [8][9][10] However, the performances including phase shifting capabilities and low insertion loss are needed to be further improved for practical applications in voltage-tunable elements.…”

Molecular Beam Epitaxial Growth and Dielectric Characterization of Ba0.6Sr0.4TiO3 Films

“…The Ba 1-x Sr x TiO 3 (BST) system is of significant technological interest owing to its nonlinear dielectric properties [1] that make it suitable for a number of microwave applications, including filters, phased arrays, and phase shifters [2][3][4][5][6]. The Curie temperature of the ferroelectric phase of this system decreases in a nearly linear fashion with x, from 400 K for BaTiO 3 to 30 K for SrTiO 3 [7].…”

“…The x = 0.4 composition, or Ba 0.6 Sr 0.4 TiO 3 , is well-studied because its Curie temperature is just below room temperature, allowing extensive tunability without hysteresis under standard operating conditions [7]. Ba 0.6 Sr 0.4 TiO 3 films were previously grown by a number of techniques, including pulsed laser deposition [1,3,4,6], sputtering [5,8], metal organic chemical vapor deposition [3,9], and sol-gel processing [7,10]. Molecular beam epitaxy (MBE) of Ba 0.6 Sr 0.4 TiO 3 has been much less studied [11].…”