Systematic investigation of the annealing temperature and composition effects on the dielectric properties of sol–gel BaxSr1−xTiO3 thin films

High-Tunability and High-<formula formulatype="inline"><tex Notation="TeX">$Q$</tex></formula>-Factor Integrated Ferroelectric Circuits up to Millimeter Waves

“…1(a) and (b)]. The grain size and the porosity changes according to the doping level and to the heat treatment temperature, and a consequent variation of the material properties is expected, as previously investigated in [17]. Concerning the BST used in this work, an equiaxial microstructure with up to 100-nm grain size has been observed.…”

“…The sol-gel process has been chosen, as it is a nondedicated and low-cost method, allowing the best control of the thin-film chemical composition compared to other BST deposition techniques. The strontium content in BST and the deposition parameters have been investigated in order to optimize the tunability and the losses of the material in the thin-film form [17], playing with the microstructure of the material. A doping strategy has also been set up to improve the leakage current, tunability, and dielectric losses of BST, combining the effect of the dopant in the perovskite lattice and at the grain boundaries [11], [18].…”

“…The influence of the strontium rate and of the recrystallization temperature have been investigated and optimized by following a strategy based on the results reported in [17]. Furthermore, different doping strategies have been compared and an innovative doping strategy has been selected in this work in order to reach the industrial specifications and to improve the dielectric properties.…”

Enhanced tunable properties of Bi1.5MgNb1.5O7 thin films grown on Pt–Si substrates using amorphous TiOx buffer layers

“…1. In this case, the structure of the BMN films are not quite effective at hindering the diffusion, and Pt atoms could easily diffuse into the BMN layers through the grain boundaries between the columns [11], as shown in Fig. 4a.…”

Combined effects of thickness, grain size and residual stress on the dielectric properties of Ba0.5Sr0.5TiO3 thin films

“…As examples, the reported out-of-plane permittivity of ∼300-nm-thick RF-sputtered BST films prepared at 600 °C on platinized silicon substrates (Ba/Sr = 50/50) with 82 nm large grains is 760 at 100 kHz [17], while the in-plane permittivity of PLD-deposited 200-nm-thick films (Ba/Sr = 60/40) on r-sapphire with grains in the 50-100 nm range is 830 at 10 GHz [21]. Besides the grain size and the thickness of the films, additional parameters that strongly influence the permittivity value are the grain morphology and porosity [26,27,43,44]. We ascribe the good dielectric properties of the films to optimized processing conditions, i.e., the separation of the drying/pyrolysis/annealing steps for the efficient removal of the organics and the high heating rate and annealing temperature of 900 °C, resulting in a dense and predominately columnar microstructure [27].…”