On the microstructure and optical properties of Ba0.5Sr0.5TiO3 films

Structure and Optical Band-Gap Energies of Ba0.5Sr0.5TiO3 Thin Films Fabricated by RF Magnetron Plasma Sputtering

“…This is possibly also a main reason for the optical band-gap energies of BST thin films obtained in our experiments being larger than that reported by other researchers. [4][5][6] In our experiments, the grain size of BST0.5 thin film sputtered at 700 C for 5 h was small and only about 28.1 nm, as measured by XRD where FWHM was 0.42 . The RMS roughness of 447-nm-thick BST0.5 thin film sputtered at 700 C, which was evaluated from the AFM image over an area of 1 mm 2 , was 1.86 nm.…”

“…The E g value for 261-nm-thick BST0.5 thin film sputtered at 700 C is 4.01 eV, which is larger than that of the bulk single crystals (3.2 eV 22) ) and those of sputtered polycrystalline (Ba x Sr 1Àx )TiO 3 thin films (3.57 -3.22 eV, x ¼ 0 { 0:9) and pulsed-laser-deposited polycrystalline (Ba 0:5 Sr 0:5 )TiO 3 thin films (3.96 eV) reported elsewhere. [4][5][6] The difference of band-gap energies between the well-crystallized films and the single crystals, it was ascribed due to the existence of grain boundaries in the polycrystalline thin films. 23) The atomic structure at the grain boundary was different from that in the grain, which led to larger free-carrier concentrations and the existence of potential barriers at the boundaries.…”

“…Recently, much attention has been paid to Ba x Sr 1Àx TiO 3 (BST) thin films fabricated on a SiO 2 /Si substrate for optical interconnection in monolithic optoelectronic integrated circuit (OEIC) device applications as they have prominent properties such as large electrooptic coefficients and relatively low optical losses. [1][2][3] Although much structural, electrical and optical data on BST thin films has been published, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] so far, there is little data available on the structural and optical properties such as optical band-gap energies of BST thin films. [4][5][6][7] The optical band-gap energy is one of the important parameters for electrooptic materials.…”

“…[1][2][3] Although much structural, electrical and optical data on BST thin films has been published, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] so far, there is little data available on the structural and optical properties such as optical band-gap energies of BST thin films. [4][5][6][7] The optical band-gap energy is one of the important parameters for electrooptic materials. Panda et al, 4) Wang and Tseng 5) and Tchelbou et al 6) respectively reported that the optical band-gap energies of BST were 3.57 -3.22 eV (x ¼ 0 { 0:9), 3.5 eV (x ¼ 0:7) and 3.96 eV (x ¼ 0:5).…”

“…[4][5][6][7] The optical band-gap energy is one of the important parameters for electrooptic materials. Panda et al, 4) Wang and Tseng 5) and Tchelbou et al 6) respectively reported that the optical band-gap energies of BST were 3.57 -3.22 eV (x ¼ 0 { 0:9), 3.5 eV (x ¼ 0:7) and 3.96 eV (x ¼ 0:5). However, no detailed corresponding structural relationship information, especially on oriented growth crystal structures, was reported.…”