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

Abstract

Thin ferroelectric barium strontium titanate (BST) layers of high structure quality have been grown for the first time directly on semi-insulating silicon carbide substrates by RF magnetron sputtering of a ceramic target. The structural and microwave properties of the films were substantially improved by an intermediate annealing of the layers during the growing process. Prepared under this approach, BST films have a well-formed crystal structure, which has a positive effect on their electrical properties, specifically on nonlinearity and dielectric losses. Planar capacitors based on these BST films demonstrate the best combination of high tunability and low losses for BST/SiC structures at microwaves.

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].…”

“…Thin BST films were deposited on SiC substrates fabricated by Svetlana-Electronpribor (St. Petersburg, Russia) [36,37] by RF magnetron sputtering of a Ba 0.4 Sr 0.6 TiO 3 ceramic target. Oxygen was used as a working gas at a pressure of 2 Pa providing optimal conditions for thin film deposition, oxidation of sputtered atoms, and crystallization of perovskite phase.…”

“…(iii) The growth of continuous 300-nm-thick BST films on SiC substrate both at T sub = 800 • C and 880 • C leads to a polycrystalline film formation [36]. (iv) The structure and microwave properties of BST films on the monocrystal substrate can be significantly improved by the multi-step deposition method using the intermediate annealing during the film growth [41], which allows us to correct the lattice defects during the layer deposition.…”

“…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.…”

Piezoresponse force microscopy and dielectric spectroscopy study of Ba0.6Sr0.4TiO3 thin films

“…The deposition of thin film functional layers on different substrates is an essential step for many fields of modern high technology. 6,7 Applications range from large area optical coatings on architectural structures to tribological layers, high-temperature superconductors, and finally to applications in micro and nanoelectronics. 3 Considering this broad spectrum of applications, it is obvious that there cannot be one perfect deposition method which can be applied in all fields.…”