Band-gap energies and structural properties of doped Ba0.5Sr0.5TiO3 thin films

Abstract

Structure and properties of W O 3 -doped Pb 0.97 La 0.03 ( Zr 0.52 Ti 0.48 ) O 3 ferroelectric thin films prepared by a sol-gel process J. Appl. Phys. 98, 034104 (2005); 10.1063/1.1999834 Effects of lanthanum doping on the dielectric properties of Ba ( Fe 0.5 Nb 0.5 ) O 3 ceramicWe have investigated the effect of Ti and Mg dopants on the structural properties and band-gap energies of Ba 0.5 Sr 0.5 TiO 3 ͑BST͒ thin films grown on LaAlO 3 substrates. The transmission spectra of these BST thin films measured by ultraviolet-visible spectrophotometer show that the band-gap energies are strongly dependent on the dopant concentration. Based on the structural analyses and theoretical calculation, the variation of the band-gap energies can be attributed to the combined effects of stress, grain size, and phase transformation in Ti-and Mg-doped BST thin films.

Reduced leakage current and conduction mechanisms of sputtered platinum-doped lead barium zirconate thin films

“…In our case, the position of this peak was shifted from 204 to 218 cm −1 (as shown by arrow marks) when the Pt concentration was increased. Such a shift towards a higher frequency value is associated with the in-plane compressive stress in the thin films [21,22], corresponding to the results observed by XRD. In brief, the differences in Raman spectra between pure and Pt-doped films are mainly caused by the stress, i.e.…”

“…The band-gap energies of the pure PBZ and the Pt(3) films were measured to be 2.77 eV and 2.97 eV, respectively, by investigating the refraction index (n) and the extinction coefficient (k). The band-gap variation has previously been observed in Ti-and Mg-doped BST thin films [21]. In our study, it can be attributed to the lattice strain caused by the existence of Pt.…”

“…Furthermore, one may distinguish between these three spectra and draw the following conclusions based on these experimental observations: (A) Near 400 cm −1 , the Raman lines of Pt-doped films are relatively broader than those found in pure PBZ films. Some possible origins of the changes in the Raman linewidths could be the disordered phases [20] which are resulted from the presence of Pt in substitutional or interstitial sites or grain size decreases [21]. The x-ray FWHM of the pure and Pt-doped films is similar and this indicates that the line broadening caused by the grain size effect can be excluded in our study.…”

Investigation of YBa2Cu3O7−δgrowth mode effect on the dielectric properties of BaxSr1−xTiO3for BaxSr1−xTiO3/YBa2Cu3O7−δbilayered thin films epitaxially grown on vicinal LaAlO3substrates

“…With increase of d YBCO , the Raman peaks for YBCO are shifted to higher-energy side, as marked with arrows. The large blue shift of about 22 cm −1 indicates that the change of the growth mode in YBCO has caused a release of in-plane compressive stress in YBCO [21,22]. As a matter of fact, a slight blue shift can also be observed in the Raman peaks for BSTO, especially for the weak peak around 733 cm −1 , indicating that the release of in-plane compressive stress identically occurs in BSTO with increase of d YBCO .…”