Structure/property relationships in ferroelectric thin films for frequency agile microwave electronics

The fabrication and material properties of compositionally multilayered Ba1−xSrxTiO3 thin films for realization of temperature insensitive tunable phase shifter devices

“…[1][2][3][4][5][6][7][8] For these tunable microwave devices, high dielectric tunability, low microwave loss, and good temperature stability are required for optimum performance and long-term reliability. Recently, much work has focused on optimizing the uniform composition BST thin film material design ͑i.e., via doping, thickness variations, buffer layers, stoichiometry, stress modification, etc.͒ and process science protocols in order to develop thin films which possess low dielectric loss and high tunability.…”

The dependence of dielectric properties on compositional variation for tunable device applications

“…It is well established for BST based films (in the frequency range between 10 kHz and 1 MHz) that there is minimal dispersion in the dissipation factor with measured frequency up to 1 MHz, however in the microwave region, 1-30 GHz, the dielectric loss becomes non-linear with frequency, and the dissipation factor, notably degrades with increasing frequency (Horwitz et al, 1998). Thus, as seen in Table 1, the measured values of dielectric loss for BST based films at low frequency (10 kHz-1 MHz) are significantly lower than the values measured at microwave frequency (10 GHz).…”

“…We suggest that the Mg doping (composition alteration) is the parameter, which is responsible for the modification of the BST thin film material properties. Material doping (independent of substrate type) has been reported to modify and control thin film dielectric and insulating properties by reducing the oxygen vacancy concentration (Cole et al, , 2001Joshi and Cole, 2000;Gopalan et al, 1999;Horwitz et al, 1998). Acceptor type dopants can prevent the reduction of Ti 4þ to Ti 3þ , by neutralizing the donor action of the oxygen vacancies.…”

The effects of drying temperature on the crystallization of YMnO3 thin films prepared by sol-gel method using alkoxides

“…The previous investigations reported that the leakage current properties of ferroelectric thin films depend upon the thin film deposition method, composition, annealing temperature, electrode, microstructure, film thickness, and surface roughness. 13 As the drying temperature of YMnO 3 thin film increases from 350 to 450 C, the leakage current density of the YMnO 3 thin films decreases. We assume that lower leakage current may be caused by the higher crystallinity and c-axis orientation of the YMnO 3 thin film.…”