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Photoconductivity and diode effect in Bi rich multiferroic BiFeO 3 thin films grown by pulsed-laser deposition

Ahadi, K ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1007/s10854-010-0217-5
  3. Publisher: 2011
  4. Abstract:
  5. Bismuth ferrite, BiFeO 3, is almost the only material that is simultaneously magnetic and a strong ferroelectric at room temperature. As a result it is the most investigated multiferroic material. In this study, bismuth ferrite thin films were deposited on silicon wafer (100) and glass by pulsed-laser deposition and their structural, optical, and electrical properties were measured. Our study indicates that Bi richness in these films can stimulate formation of oxygen vacancy in the system which in its turn leads to delocalization of carriers and a more intensified photoconductivity response. X-ray diffraction analysis revealed formation of BiFeO 3 (BFO), but it also showed formation of Bi 2O 3 and Bi 2O 2.3 as well as BFO. Energy dispersive spectrum (EDS) also showed higher atomic concentration of Bi with respect to Fe. It also disclosed Bi depletion through the films during post-growth heat treatment. Atomic force microscopy showed a homogeneous nano structure with columnar grains. It also disclosed that higher substrate temperature can improve smoothness of the films. Scanning electron microscopy depicted the thickness of about 200 nm. Transmission spectrum illustrated band gap of about 2 eV. Dark-light IV characteristics were conducted on the films which were subjected to post-growth heat treatment at 0.01 and 760 Torr O2. Dark conductivities increased by an order of magnitude in comparison between films which were subjected to postgrowth heat treatment at 0.01 and 760 Torr O2. Dark-light IV characteristics of the films also uncovered a remarkable increase in conductivity under illumination in comparison to dark one. Diode behavior of the films was investigated by IV characteristics as well
  6. Keywords:
  7. Atomic concentration ; Bismuth ferrites ; Columnar grain ; Dark conductivity ; Delocalizations ; Diode effects ; Energy dispersive spectrum ; IV characteristics ; Multiferroic materials ; Multiferroics ; Room temperature ; Substrate temperature ; Transmission spectrums ; Atomic force microscopy ; Atomic spectroscopy ; Crystal atomic structure ; Deposition ; Ferrite ; Ferrites ; Glass lasers ; Heat treatment ; Oxygen vacancies ; Photoconductivity ; Photoelectricity ; Pulsed laser deposition ; Pulsed lasers ; Scanning electron microscopy ; Semiconducting silicon compounds ; Silicon wafers ; Thin films ; Vapor deposition ; X ray diffraction ; X ray diffraction analysis ; Bismuth
  8. Source: Journal of Materials Science: Materials in Electronics ; Volume 22, Issue 7 , 2011 , Pages 815-820 ; 09574522 (ISSN)
  9. URL: http://link.springer.com/article/10.1007%2Fs10854-010-0217-5