Preparation of (Ba, Sr)TiO₃ Thin Films with High Pyroelectric Coefficients at Ambient Temperatures

Abstract

Ferroelectric barium strontium titanate (BST) thin films were grown on Pt/Ta 2 O 5 /SiO 2 /Si by sputtering Ba 0.66 Sr 0.34 TiO 3 targets containing different amounts of excess SrO. It was found that the excess SrO in the target strongly influenced the microstructures and pyroelectric properties of the BST films. Compared with the BST film grown using a target without excess SrO, BST films grown using targets containing excess SrO of 0.02-0.04 by molar fraction showed larger grains and higher tendency to grow along (200) orientation, resulting in better pyroelectric characteristics at ambient temperatures. We obtained BST films with a considerably high pyroelectric coefficient of 240 nC·cm −2 ·K −1 .

Intrinsic pyroelectric properties of thick, coarse grained Ba 1−x Sr x TiO 3 ceramics

“…In any case, the values obtained for the intrinsic pyroelectric coefficient, without applied electric field, are comparable if not slightly better than previous studies reporting room temperature values (with or without applied electric field) of: about 10 -3 C/m 2 K for BST with 30 % or 33 % Sr content [4,16,22,52], with the mention that 33 % Sr means a lower transition temperature, leading to better pyroelectric properties; total value of (1-4)u10 -3 C/m 2 K for BST with 30 % Sr content, with an applied field of 700 Vmm -1 , including thus the induced part of the pyroelectric coefficient [17]; up to 4u10 -4 C/m 2 K for BST with 30 % Sr, doped with Mn or Y, with an applied field of 400 Vmm -1 [19]; up to 2u10 -4 C/m 2 K for undoped BaTiO 3 thick films and ceramics [67,68]. The values in Table 3 can be further enhanced by doping and by applying an external electric field on the active pyroelectric element in order to increase the contribution of the induced pyroelectric coefficient to the total pyroelectric coefficient defined by equation (1).…”

“…The intrinsic part p was only rarely studied, usually in compositions with transitions around room temperature [4,22]. In all the above mentioned references the pyroelectric coefficient was estimated from the temperature dependence of the pyroelectric current, assuming a constant heating rate.…”

Ultraviolet radiation detection by barium titanate thin films grown by sol–gel hydrothermal method

“…Ferroelectric thin films were also important for tunable microwave devices, acoustic and pressure sensors, surface acoustic wave devices, MEMS and actuator applications [1]. Few reports are also available on realization of UV photodetectors using ferroelectric thin films by combining their unique optical and piezoelectric properties [2][3][4][5][6][7][8][9]. In the last two decades, there has been increasing demand for reliable photodetectors for detection of UV radiation due to its harmful effects [10].…”

Modified Spin Coating Method for Coating and Fabricating Ferroelectric Thin Films as Sensors and Solar Cells

“…Ferroelectric thin films such as barium strontium titanate, lithium tantalate, and lithium niobate can be manufactured by using CSD method and then performed by the spin coating process [1]. CSD method is one of the methods to create/develop thin films [2][3][4][5][6][7][8][9][10][11][12], which has advantages including the ability to control the film stoichiometry with good quality, easy procedure, require relatively low cost, and generate a good crystalline phase [13][14][15]. In addition, thin films can also be fabricated by other methods such as metal organic chemical vapor deposition (MOCVD) [16][17][18], chemical vapor deposition [19], sol-gel [20][21][22][23], atomic layer deposition (ALD) [24], metal organic decomposition (MOD) [25], pulsed laser ablation deposition (PLAD) [26,27], and RF sputtering [2,21,28].…”