Mn Co-doped BiFeO3 Thin Films Research Articles

Photovoltaic Effect of La and Mn Co-Doped BiFeO3 Heterostructure with Charge Transport Layers.

Bismuth ferrite BiFeO3 (BFO)-based ferroelectrics have great potential as inorganic perovskite-like oxides for future solar cells applications due to their unique physical properties. In this work, La and Mn co-doped BFO thin films with compositions Bi0.9La0.1(Fe1-xMnx)O3 (x = 0, 0.05, 0.1, 0.15) (denoted as BLF, BLFM5, BLFM10, BLFM15, respectively) were prepared via a sol-gel technique on indium tin oxide (ITO) glass. All the films are monophasic, showing good crystallinity. The optical bandgap Eg was found to decrease monotonously with an increase in the Mn doping amount. Compared with other compositions, the BLFM5 sample exhibits a better crystallinity and less oxygen vacancies as indicated by XRD and XPS measurements, thereby achieving a better J-V performance. Based on BLFM5 as the light absorbing layer, the ITO/ZnO/BLFM5/Pt and ITO/ZnO/BLFM5/NiO/Pt heterostructure devices were designed and characterized. It was found that the introduction of the ZnO layer increases both the open circuit voltage (Voc) and the short circuit current density (Jsc) with Voc = 90.2 mV and Jsc = 6.90 μA/cm2 for the Pt/ BLFM5/ZnO/ITO device. However, the insertion of the NiO layer reduces both Voc and Jsc, which is attributed to the weakened built-in electric field at the NiO/BLFM5 interface.

Effect of substrate temperature on the structural and electrical properties of La and Mn co-doped BiFeO3 thin films

The effect of substrate temperature on the structural and electrical properties of multiferroic Bi0.90La0.10Fe0.95Mn0.05O3 (BLFMO) thin films deposited on Pt (111)/Ti/SiO2/Si substrate using pulsed laser deposition (PLD) has been investigated. Films with substrate temperature ranging from 450°C to 650°C have been deposited. The grain size and roughness are found to increase with substrate temperature. The film deposited at 575°C exhibits maximum remnant polarization around 39μC/cm2 and a coercive field of 400kV/cm. The cyclic fatigue study of the sample shows only 4% loss after 108cycles. Complex impedance study of the BLFMO thin films demonstrates electrical homogeneity of the sample. AC conductivity data has been fitted using Jonscher single power law, and value of n found to be <1 indicating translational hopping conduction mechanism. The lowest leakage current found is 4.37×10−6A/cm2 at 575°C. The leakage current mechanism is found to be dominated by space charge limited current and Fowler-Nordheim conduction mechanism.

Effects of Ho, Mn co-doping on ferroelectric fatigue of BiFeO3 thin films

Ho, Mn, and Ho, Mn co-doped BiFeO3 thin films were deposited on Pt (100)/Ti/SiO2/Si substrates using solution gelation. The ferroelectric fatigue properties were clearly improved after doping with Ho and Mn. The doped BiFeO3 thin film displayed more strongly increased ferroelectric, leakage current, and fatigue properties compared with the pure BiFeO3 thin film. Thus, the improved performance of the BiFeO3 thin films depends on the structural transformation and reduced oxygen vacancy concentration. The present work provides a feasible approach to enhance the ferroelectric and fatigue properties of BiFeO3-based thin films. Open image in new window

Effect of Ho and Mn co-doping on structural, ferroelectric and ferromagnetic properties of BiFeO3 thin films

Multiferroic pure, Ho doped, Mn doped, as well as Ho, Mn co-doped BiFeO3 thin films were prepared using a sol–gel technique. The effect of Ho and Mn co-doping on the structure, ferroelectric and ferromagnetic properties of BiFeO3 films was studied in detail. It shows that the enhanced ferroelectric polarization and magnetization were obtained after doping Ho and Mn. Such enhanced ferroelectric properties are attributed to ferroelectric distortion derived from the structural transformation and microstructure improvement after doping Ho and Mn. The enhanced ferromagnetic properties are attributed to the uncompensated surface spins and the release of the latent magnetization locked within the cycloid induced by doping Ho and Mn. The present work provides an easy method to enhance the ferroelectric and ferromagnetic properties of BiFeO3 based magnetoelectric multiferroic films.

Structural, electric and magnetic properties of Dy and Mn co-doped BiFeO3 thin films

Pure BiFeO3 (BFO), Dy-doped BiFeO3 (BDFO) and Dy-Mn co-doped BiFeO3 (BDFMO) thin films were successfully prepared on SnO2: F (FTO)/glass substrates by a sol-gel method. The effects of Dy-doping and Dy-Mn co-doping on the crystal structure, dielectric, ferroelectric and ferromagnetic properties of the BFO thin films were studied. In the Dy-doped and Dy-Mn co-doped BFO thin films, a structural transition from the trigonal structure (R3c:H) to the trigonal structure (R3m:R) was demonstrated by XRD, Rietveld refinement and Raman spectra analyses. It׳s obvious that the multiferroic properties of the BDFMO thin film were improved in comparison with the BFO thin film. Furthermore, a high enhancement in multiferroic properties with a giant remanent polarization (Pr=96.5 μC/cm2) and a relative large saturation magnetization (Ms=8.70emu/cm3) was observed in the BDFMO thin films.

Resistive switching properties of Ce and Mn co-doped BiFeO3 thin films for nonvolatile memory application

The Ce and Mn co-doped BiFeO3 (BCFMO) thin films were synthesized on Pt/Ti/SiO2/Si substrates using a sol-gel method. The unipolar resistive switching (URS) and bipolar resistive switching (BRS) behaviors were observed in the Pt/BCFMO/Pt device structure, which was attributed to the formation/rupture of metal filaments. The fabricated device exhibits a large ROFF/RON ratio (&amp;gt;80), long retention time (&amp;gt;105 s) and low programming voltages (&amp;lt;1.5 V). Analysis of linear fitting current-voltage curves suggests that the space charge limited leakage current (SCLC) and Schottky emission were observed as the conduction mechanisms of the devices.

Electrical properties of Dy, Mn Co-doped BiFeO3 thin films prepared by using chemical solution deposition

The effects of Dy, Mn alone doping and co-doping on the structural, electrical and ferroelectric properties of BiFeO3 thin films were investigated. (Bi1−x Dy x )(Fe1−y Mn y )O3 thin films, with (x, y) = (0, 0), (1, 0), (0, 1), and (1, 1) denoted by BFO, BDyFO, BFMnO, and BDyFMn, respectively, were prepared by using a chemical solution deposition method. All thin films were annealed at 550 °C for 30 min by using a conventional annealing process under a nitrogen atmosphere for crystallization. Among the thin films, superior ferroelectric properties were observed in the BDyFMn thin film. The BDyFMn thin film exhibited a low leakage current density (1.8 × 10−5 A/cm2), well-saturated hysteresis loops, a large remanent polarization (2P r ) of 80 µC/cm2 (at a 1060-kV/cm applied electric field) and good fatigue endurance.

Influence of pyrolysis temperature on ferroelectric properties of La and Mn co-doped BiFeO3 thin films

Bi0.9La0.1Fe0.95Mn0.05O3 (BLFMO) ferroelectric thin films were fabricated on Pt/Ti/SiO2/Si/substrates by the sol-gel process at different pyrolysis temperatures. The mass loss of BLFMO powder was investigated by thermo gravimetry analyser (TGA), and the polycrystalline structure and smooth surface of BLFMO thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The remnant polarization (Pr) of the BLFMO films pyrolyzed at 420°C is 21.2 μC/cm2 at the coercive field (Ec) of 99 kV/cm and the leakage current density is 7.1×10−3 A/cm2, which indicates that the BLFMO thin films display relatively good ferroelectric property at this temperature.

Preparation and Electrical Properties of Bi&lt;sub&gt;0.9&lt;/sub&gt;Nd&lt;sub&gt;0.1&lt;/sub&gt;Fe&lt;sub&gt;0.925&lt;/sub&gt;Mn&lt;sub&gt;0.075&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Thin Films

Pure BiFeO3(BFO) and Bi0.9Nd0.1Fe0.925Mn0.075O3(BNFM) thin films were deposited on Pt(111)/Ti/SiO2/Si substrate by sol-gel method. X-ray diffraction analysis showed that all the films were single perovskite structure and a phase transition appeared in Nd–Mn codoped BiFeO3 thin films. Electrical measurements indicated that the ferroelectric properties of BFO thin films were significantly improved by Nd and Mn codoping. BNFM films exhibit a low leakage current and a good P-E hysteresis loop. The remanent polarization (Pr) value of 74μC/cm2has been obtained in BNFM films, while the coercive field (Ec) is 184kV/cm.

Reduced leakage current and improved ferroelectric properties of Eu and Mn codoped BiFeO3 thin films

We prepared (Bi0.94Eu0.06)(Fe0.94Mn0.06)O3 (BEFM), (Bi0.94Eu0.06)FeO3 (BEFO), and BiFeO3 (BFO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a pulsed laser deposition method. X-ray diffraction and Raman scattering results showed that the rhombohedral structure of the BFO film was not affected by the substitution of Eu and Mn ions. A much reduced leakage current was observed in the BEFM thin film capacitor compared to the BEFO and BFO thin film capacitors. Higher electrical breakdown field was observed in the BEFM and BEFO thin film capacitors than in the BFO thin film capacitor.

Structural transitions and enhanced ferroelectricity in Ca and Mn co-doped BiFeO3 thin films

Ca and Mn co-doped BiFeO3 (BFO) thin films were fabricated on (111) Pt/Ti/SiO2/Si substrates via a simple solution approach. Enhanced ferroelectric properties were obtained in these Ca and Mn co-doped BFO films, e.g., large remnant polarization value (Pr ∼ 89 μC/cm2) and large remnant polarization to saturated polarization ratio (Pr/Ps ∼ 0.84) for Bi0.90Ca0.10Fe0.90Mn0.10O3 film. X-ray diffraction and Raman spectra of these films showed that B-site Mn doping causes substantial structural transition toward orthorhombic phase and A-site Ca doping facilitates an evolution to tetragonal phase with higher crystal symmetry. The structural transitions are in favor of enhanced ferroelectric properties in the BFO films. The approach of A and B site co-doping is proved to be effective in enhancing ferroelectric performance in multiferroic BFO films.