Characterization of non-stoichiometric co-sputtered Ba0.6Sr0.4(Ti1 − x Fe x )1 + x O3 − δ thin films for tunable passive microwave applications

Abstract

The fabrication of novel iron-doped barium strontium titanate thin films by means of radio frequency (RF) magnetron co-sputtering is shown. Investigations of the elemental composition and the dopant distribution in the thin films obtained by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and time-of-flight secondary ion mass spectroscopy reveal a homogeneous dopant concentration throughout the thin film. The incorporation of the iron dopant and the temperature-dependent evolution of the crystal structure and morphology are analyzed by electron paramagnetic resonance spectroscopy, X-ray diffraction, Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. In summary, these results emphasize the RF magnetron co-sputter process as a versatile way to fabricate doped thin films.

Polymerizable Ceramic Ink System for Thin Inkjet-Printed Dielectric Layers

“…For the pure BST powder, the binding energies of Ti 4+ (2p 3/2 , 458.2 eV), Ba 2+ (3d 5/2 , 778.4 eV), and Sr 2+ (3d 5/2 , 132.9 eV) are detected accordingly to the literature. − In the case of barium, an additional signal was detected at 780.0 eV, which could be either BaCO 3 or Ba­(OH) 2 on the surface, as described in the literature. ,− When the calcination of the BST powder is not fully completed, small amounts of BaCO 3 can be present. However, as no carbonate can be found in the C 1s spectrum (expected at ∼289.7 eV), this peak is most likely assigned to Ba­(OH) 2 on the surface.…”

Effects of thermal processing and iron doping in co-sputtered barium strontium titanate thin films

“…The broad resonance at *340 mT represents octahedral coordinated Fe 3? cations incorporated at the B-site of the perovskite structure [17,21,39]. The corresponding signal intensity is invariant upon temperature.…”

“…1). Various amounts of such foils were used to tune the iron stoichiometry within the films via the resulting target area ratios of the dopant and the BST base target [17,22,23].…”

“…In a previous study, we presented RF magnetron co-sputtering as a suitable way to achieve novel irondoped BST thin films [17]. Herewith, it is possible to achieve a homogenous dopant distribution throughout the film and, thus incorporate the dopant into the perovskite crystal structure.…”

“…Friederich et al and other groups [14][15][16] have shown that the grain diameter strongly influences the tunability of the thick films and therefore superimpose the influence originated from the dopants. In our approach of co-sputtered Fe-doped BST thin films these effects can be separated [17].…”