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Title: Low-temperature crystallized pyrochlore bismuth zinc niobate thin films by excimer laser annealing

Abstract

The crystallization temperature of Bi{sub 1.5}Zn{sub 0.5}Nb{sub 1.5}O{sub 6.5} (BZN) films was reduced by a combination of conventional heating and irradiation with a pulsed KrF excimer laser. Both the energy density and substrate temperature affect the properties of laser-annealed BZN films. It was found that the crystallinity and dielectric properties improved after a postannealing at 400 deg. C for 2 h in an oxygen atmosphere. BZN films crystallized with an energy density of 27 mJ/cm{sup 2} at a substrate temperature of 400 deg. C with postannealing showed dielectric properties comparable to those of rapid thermal annealed BZN films. Laser crystallization at substrate temperatures {<=}400 deg. C makes integration with polymeric substrates possible.

Authors:
; ; ;  [1]
  1. Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
Publication Date:
OSTI Identifier:
20706468
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 87; Journal Issue: 23; Other Information: DOI: 10.1063/1.2140071; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; ATMOSPHERES; BISMUTH COMPOUNDS; CRYSTALLIZATION; DIELECTRIC MATERIALS; ENERGY DENSITY; HEATING; IRRADIATION; KRYPTON FLUORIDE LASERS; NIOBATES; OXYGEN; PERMITTIVITY; PYROCHLORE; REFRACTIVE INDEX; SUBSTRATES; TEMPERATURE RANGE 0400-1000 K; THIN FILMS; ZINC COMPOUNDS

Citation Formats

Cheng, J.-G., Wang Junling, Dechakupt, Tanawadee, and Trolier-McKinstry, Susan. Low-temperature crystallized pyrochlore bismuth zinc niobate thin films by excimer laser annealing. United States: N. p., 2005. Web. doi:10.1063/1.2140071.
Cheng, J.-G., Wang Junling, Dechakupt, Tanawadee, & Trolier-McKinstry, Susan. Low-temperature crystallized pyrochlore bismuth zinc niobate thin films by excimer laser annealing. United States. doi:10.1063/1.2140071.
Cheng, J.-G., Wang Junling, Dechakupt, Tanawadee, and Trolier-McKinstry, Susan. Mon . "Low-temperature crystallized pyrochlore bismuth zinc niobate thin films by excimer laser annealing". United States. doi:10.1063/1.2140071.
@article{osti_20706468,
title = {Low-temperature crystallized pyrochlore bismuth zinc niobate thin films by excimer laser annealing},
author = {Cheng, J.-G. and Wang Junling and Dechakupt, Tanawadee and Trolier-McKinstry, Susan},
abstractNote = {The crystallization temperature of Bi{sub 1.5}Zn{sub 0.5}Nb{sub 1.5}O{sub 6.5} (BZN) films was reduced by a combination of conventional heating and irradiation with a pulsed KrF excimer laser. Both the energy density and substrate temperature affect the properties of laser-annealed BZN films. It was found that the crystallinity and dielectric properties improved after a postannealing at 400 deg. C for 2 h in an oxygen atmosphere. BZN films crystallized with an energy density of 27 mJ/cm{sup 2} at a substrate temperature of 400 deg. C with postannealing showed dielectric properties comparable to those of rapid thermal annealed BZN films. Laser crystallization at substrate temperatures {<=}400 deg. C makes integration with polymeric substrates possible.},
doi = {10.1063/1.2140071},
journal = {Applied Physics Letters},
number = 23,
volume = 87,
place = {United States},
year = {Mon Dec 05 00:00:00 EST 2005},
month = {Mon Dec 05 00:00:00 EST 2005}
}
  • Cubic bismuth zinc niobate pyrochlore (base composition (Bi{sub 1.5}Zn{sub 0.5})(Zn{sub 0.5}Nb{sub 1.5})O{sub 7}) powders were successfully prepared by a chemical method. The formation mechanism of the pyrochlore phase was investigated by TG-DSC, FT-IR, Raman, and X-ray diffraction (XRD). The optical bandgap for the powders treated at temperatures ranging from 500 to 700 deg. C is 3.0-3.1eV, indicating low crystallization temperature for the pyrochlore phase. No detectable intermediary phases as BiNbO{sub 4} or a pseudo-orthorhombic pyrochlore were observed at any time and the cubic-BZN phase was already formed after thermal treatment at temperatures as low as 500 deg. C. The phasemore » formation study reveals that a well-crystallized single-phased nanopowder is obtained after calcination at 700 deg. C, indicating that the chemical synthesis conferred a higher chemical homogeneity and reactivity on the powder, modifying the crystallization mechanism.« less
  • It is well known that the cubic pyrochlore Bi{sub 1.5}ZnNb{sub 1.5}O{sub 7} exhibits higher permittivity and dielectric loss than monoclinic Bi{sub 2}Zn{sub 2/3}Nb{sub 4/3}O{sub 7} due to structural disorder in the A sites of Bi{sub 1.5}ZnNb{sub 1.5}O{sub 7}. We have studied systematically the impact of the ion substitution in the A site of monoclinic Bi{sub 2}Zn{sub 2/3}Nb{sub 4/3}O{sub 7} on the structure and microwave dielectric properties. It is shown that the structure and permittivity of (Bi{sub 1.92}M{sub 0.08})(Zn{sub 0.64}Nb{sub 1.36})O{sub 7} (M=Zn,Ca,Cd,Sr,Ba) ceramics remain almost the same as in Bi{sub 2}Zn{sub 2/3}Nb{sub 4/3}O{sub 7}; only the Ba substituted ceramics havemore » higher permittivity due to multiphase structure. Microwave dielectric properties were compared with complex dielectric response in terahertz and infrared frequency range of 0.1-100 THz, which allows us to estimate intrinsic and extrinsic contributions to microwave dielectric losses. The best microwave properties were obtained in (Bi{sub 1.92}Ca{sub 0.08})(Zn{sub 0.64}Nb{sub 1.36})O{sub 7} with {epsilon}=76, Qf{>=}5000 (sintered below 950 deg.C), which is promising for microwave low temperature cofiring ceramic application.« less
  • The as-grown crystallized films of low T/sub c/ phase (T/sub c//similar to/80 K) in a Bi-Sr-Ca-Cu-O system were prepared by rf magnetron sputtering and were annealed in argon or oxygen atmosphere below 500 /sup 0/C. Superconducting properties and the c-axis lattice constant varied according to the annealing temperature and atmosphere. These results suggest that the oxygen content in the film is varied by low-temperature annealing and that the variation of oxygen content affects the superconducting and structural properties. By cooling the sample in the chamber in 760 Torr oxygen, the as-grown film with T/sub c/ end at 74 K wasmore » obtained.« less
  • In a previous work, we reported the high field effect mobility of ZnO-doped In{sub 2}O{sub 3} (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to amore » high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.« less
  • Amorphous sputter-deposited NiTi thin films were subjected to pulsed, melt-mediated laser crystallization techniques to engineer their microstructure. The effects of laser processing of preheated films are examined. Laser processing of films at an elevated substrate temperature has a significant effect on the rate with which solidification occurs. It is observed that the preheating temperature at which processing is carried out has significant implications for the resulting phase and microstructure, and therefore mechanical properties. Furthermore, the microstructural effects of varying incident laser energy density are examined via atomic force microscopy, scanning electron microscopy, and x-ray diffraction, and mechanical/shape memory properties aremore » characterized via nanoindentation.« less