Measurement of Microwave Dielectric Properties of (Sr,Ba)Nb₂O₆ Thin Films

Abstract

001) oriented (Sr,Ba)Nb 2 O 6 (SBN) thin films were deposited on MgO (001) single crystal substrates by the pulsed laser deposition method. Structural properties of SBN films were investigated using X-ray diffractometer. The microwave dielectric properties of SBN films were examined by calculating the scattering parameter obtained using a HP 8510C vector network analyzer with the frequency range 0.5-20 GHz at room temperature under the dc bias field of 0-80 kV/cm for interdigital capacitors (IDT) and coplanar waveguide (CPW) device based on SBN/MgO layer structure. Thick metal electrode patterns were fabricated by dc sputtering deposition, photolithography and etching process. The IDT device based on (001) oriented SBN films exhibited about 40% capacitance tunability with an electric field change of 80 kV/cm at room temperature, and the dielectric quality factor was about 20 at 12 GHz with no dc bias.

Strontium Barium Niobate Thin Films for Dielectric and Electro-Optic Applications

“…A value of 0.25% cm/kV at low frequency (1MHz) was recently presented as an excellent result for BST thin films (Nozaka et al, 2008). The electrical tunability of SBN thin films prepared by PLD on MgO substrates has been measured by Moon et al between 0.5 and 20 GHz and found to be 0.5% cm/kV (Moon et al, 2004). The same authors compared phase shifters based on (Ba, Sr)TiO 3 and SBN thin films between 0.5 and 20 GHz, and concluded that these two materials were competitors for microwave tunable devices (Moon et al, 2005).…”

Enhanced Tunable Properties of Strontium Barium Niobate Films on Dielectric Alumina Substrate at Microwaves

“…In this case, strontium barium niobate Sr x Ba 1−x N 2 O 6 (SBN) looks more attractive compared to BST in terms of the dielectric nonlinearity, since the smaller niobium ion provides a greater ionic displacement than the titanium one (R Nb = 0.69 Å < R Ti = 0.75 Å) [7,8]. In addition, strontium barium niobate in thin film form exhibits high permittivity values at 2 of 13 relatively low losses at microwaves [9], which makes it promising as a nonlinear material of tunable microwave devices.…”

“…At the same time, much fewer articles are devoted to the study of the dielectric and tunable properties of strontium barium niobate [31]. Today, studies on the dielectric properties of SBN films grown on silicon [32,33], magnesium oxide [9,34], and strontium titanate substrates [35,36] have been published. The vast majority of the mentioned publications provide data on the dielectric properties of SBN films in the frequency range of 1-100 kHz.…”

“…In the few works dedicated to the growth of SBN layers on dielectrics, as well as the study of their microwave properties [9,38], single-crystal MgO and LaAlO 3 are used as substrates. The choice of substrates similar in structure to the deposited material makes it possible to obtain oriented films; however, both lanthanum aluminate and magnesium oxide are not optimal substrates for microwave applications: LaAlO 3 due to high cost and anisotropy of properties, and MgO due to hygroscopicity and degradation of properties over time.…”