Ferroelectric films of barium strontium titanate on semi-insulating silicon carbide substrates

Abstract

Thin ferroelectric Ba x Sr 1 -x TiO 3 (BST) layers have been grown for the first time on semi-insulating silicon carbide substrates by RF magnetron sputtering of a ceramic target without using buffer sublayers. Results of investigation of the structure of obtained BST films and the electrical properties of related planar capacitors are presented. The obtained structures are characterized by high nonlinearity and low dielectric losses at microwave frequencies.

Heterostructures “Ferroelectric Film/Silicon Carbide” for High Power Microwave Applications

“…For all BST capacitors tested, tan δ was in the range from 0.02 to 0.03. BST/SiC structures obtained in this work demonstrate combination of high tunability and low losses that distinguishes favorably from the values reported in the literature for BST films on silicon carbide [32,33,35,36].…”

“…BST planar capacitors on semi-insulating SiC characterized at microwave frequencies were demonstrated in [35] and the oriented growth of BST film directly on SiC for the first time was described in [36]. All these works have analyzed the small-signal characteristics of BST films on silicon carbide but PHC studies have not been performed on BST/SiC structures.…”

Structural and microwave characterization of BaSrTiO3 thin films deposited on semi-insulating silicon carbide

“…26,27) The resistivity of SiC substrates measured by a contactless technique was about 10 12 Ω•m, the typical losses at 6 GHz amounted to tan δ ∼ 10 −4 , and the surface roughness was below 1 nm. 21) Thin BST films on SiC substrates were obtained by RF magnetron sputtering of a ceramic target with Ba 0.4 Sr 0.6 TiO 3 composition. The choice of this composition with high strontium content was related to the need in obtaining thin films in the paraelectric state with low dielectric losses in the microwave range.…”

“…The most extensively studied FE materials that can be used at microwave frequencies are solid solutions of barium and strontium titanates Ba x Sr 1−x TiO 3 (BST) because of the good combination of high tunability and low MW losses. [15][16][17][18] There are not a lot of publications [19][20][21] that describe attempts to obtain BST films on SiC substrates. First of these works was devoted to studying BST films on semiconductor SiC, 19) while the second 20) presented experimental data on a dielectric losses (tan δ) in parallel-plate capacitive structures (which are not suitable for high power applications) in a lowfrequency range of 1-100 kHz (with rather high level of tan δ within 0.01-0.025), from which it is impossible to judge the applicability of obtained films in the microwave range.…”

“…A principal possibility of preparing thin BST capacitive planar elements on semi-insulating SiC, which are suitable for MW applications, for the first time was demonstrated in Ref. 21. Nevertheless, the prepared films are second in nonlinearity and Q-factor to BST=sapphire structures, 22) which indicates the necessity of detailed designing technological approaches to deposition of multicomponent FE films on silicon carbide.…”