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Borges Carvalho, Nuno

Bouca, Patricia

Costa, M. Elizabete

Serrazina, Ricardo

Tkach, Alexander

Vilarinho, Paula M.

Włódarkiewicz, Anna

English

Engineering Conferences International

HIGH FREQUENCY CHARACTERIZATION AND NONLINEAR ANALYSIS OF BST THICK FILMS PRODUCED BY ELECTROPHORECTIC DEPOSITION  Paula M. Vilarinho, Department of Materials and Ceramic Engineering, CICECO - Aveiro Institute of Materials, University of Aveiro, Portugal paula.vilarinho@ua.pt  Patricia Bouca, Institute of Telecomunications – Aveiro, University of Aveiro, Portugal Anna Włódarkiewicz, CICECO - Aveiro Institute of Materials, University of Aveiro, Portugal Ricardo Serrazina, CICECO - Aveiro Institute of Materials, University of Aveiro, Portugal Alexander Tkach, CICECO - Aveiro Institute of Materials, University of Aveiro, Portugal M. Elizabete Costa, CICECO - Aveiro Institute of Materials, University of Aveiro, Portugal Nuno Borges Carvalho, Institute of Telecomunications – Aveiro, University of Aveiro, Portugal   Key Words: Electrophorectic Deposition, Barium Strontium Titanate, Thick films, RF characterization, nonlinear analysis.  Electrophoretic Deposition (EPD) is one of the most versatile process to fabricate electroceramic films for electronic devices. It has been a challenge to use low cost and sustainable processes that allows radio frequency (RF) electronic devices to integrate tunable room temperature films with classic electronic circuits. To respond to these needs, Barium Strontium Titanate (BST) films are proposed as the answer to adaptative RF microstrip based devices such as filters and antennas.  Commercial BST thick films have been used as tunable capacitors to produce the best RF devices in terms of metrics, such as tunability.   However, commercial devices have not been explored to its maximum capabilities. For thick films of BST deposited by EPD using a probe station for RF characterization, the s-parameters are measured and a model for these films is extracted. A deep pursuit on producing a ceramic film is an essential task to establish how the fabrication conditions such as grain sizes, sintering temperature, and electrodes thickness, may play their role in the tunability, nonlinearity and memory effects in RF.  Homogeneous and dense microstructure, Fig.1, 𝐵𝐵𝑎𝑎0.7𝑆𝑆𝑟𝑟0.3𝑇𝑇𝑇𝑇𝑂𝑂3 thick films deposited from acetone with iodine-based suspensions in Pt foil exhibit very good dielectric properties, Fig.2. During EPD cycles performance there is no visible degradation on the deposition in the first 2 hours. After that the suspension loses stability, possibly suffering from aging due to lixiviation of BST powders.  The results presented in Fig. 2 indicates a tunability up to 50% at 1KHz with quite low loss tangent. Due to this fact, these BST films are of most interest to be studied not only because of the electrical properties, but also the due to the phase transition at room temperature related to the ratios of Barium and Strontium. It is a new challenging issue to understand how the ferroelectric and paraelectric phases will impact in the nonlinear characteristics of the presented films at RF.   Fig.1: SEM micrographs of 𝑩𝑩𝒂𝒂𝟎𝟎.𝟕𝟕𝑺𝑺𝒓𝒓𝟎𝟎.𝟑𝟑𝑻𝑻𝑻𝑻𝑶𝑶𝟑𝟑 films sintered at 1350°C/h  Fig.2: Relative permittivity and loss tangent as a function of bias voltage of BST films deposited from acetone with iodine-based suspensions. 

High Frequency Characterization and Nonlinear Analysis of BST Thick Films Produced by Electrophoretic Deposition

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1009&context=epdvii&type=additional

High Frequency Characterization and Nonlinear Analysis of BST Thick Films Produced by Electrophoretic Deposition

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Engineering Conferences International