La 0.8 Sr 0.2 MnO 3 buffer layer effects on microstructure, leakage current, polarization, and magnetic properties of BiFeO3 thin films

Abstract

BiFeO 3 thin films were processed on La0.8Sr0.2MnO3 (LSMO) buffered silicon substrate via chemical solution deposition. Short-wave ultraviolet assisted pyrolysis was conducted in oxygen atmosphere in order to improve microstructure. A fine, homogeneous, and phase-pure grain structure with smooth topography was obtained. X-ray photoelectron spectroscopy analysis indicates diffusion of lanthanum and manganese from LSMO into the BiFeO3 film leading to a diffuse interface. Nevertheless, improved polarization and leakage resistance properties were obtained. For the first time polarization switching was obtained in sol-gel BiFeO3 films using capacitance-voltage (C−V) curves. This has been imputed to homogeneous local electrical properties of the film, corroborated by surface scanning potential microscopy investigations. The leakage current mechanisms were investigated as function of temperature, and could be interpreted in terms of the Frenkel-Poole mechanism with a trap depth of 1.6 eV. Finally, the magnetic properties of the LSMO∕BiFeO3 heterostructure are presented in comparison to those of BiFeO3 on platinized silicon. An exchange coupling between BiFeO3 and LSMO layers is suggested.

Effect of the thickness of BiFeO3 layers on the magnetic and electric properties of BiFeO3/La0.7Sr0.3MnO3 heterostructures

“…Figure 2(c) shows the BFO layer thickness dependence of the ferromagnetic transition temperature T c (calculated value from the Curie-Weiss law v¼ C TÀT c , where v is the magnetic susceptibility, C is a material-specific Curie constant, T is absolute temperature, and T c is the Curie temperature) and the magnetic coercive field H c at 10 K. Both values of T c and H c of BFO/LSMO/ STO heterostructures are higher than those of the bare LSMO film without BFO, consistent with previous experimental results. 6,24 This may be due to the exchange coupling at the ferromagnetic-antiferromagnetic interface. 6,25 As a result of this exchange coupling, the ferromagnetic order can be maintained at the temperature above T c (325 K) of the bare LSMO film without BFO, which leads to a higher transition temperature and a larger magnetic coercive field for the BFO/LSMO/STO heterostructures.…”

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

“…370 In addition, in order to gain a large remnant polarization, BFO homostructure films have to be tuned into appropriate film orientation. [359][360][361][362][363][364][365] Conductive oxide buffer layers have often been used to grow bismuth ferrite thin films and improve their properties 23,67,69,78,225,328,[390][391][392][393][394][395][396] by controlling the film texture as well as tuning the leakage current. 23,67,69,78,225,328,[390][391][392][393][394][395][396] .…”

Effects of Ho and Ti Doping on Structural and Electrical Properties of BiFeO3 Thin Films

“…Particularly, BFO thin film fabricated via a chemical solution deposition (CSD) method showed relatively large leakage and poor hysteresis behavior compared to other sophisticated techniques, such as laser ablation process, molecular beam epitaxy, and metal organic chemical vapor deposition . However, wet chemistry‐based CSD technique has many advantages, such as uniformity of the molecules in precursor solution, film fabrication in ambient pressure, cost‐effectiveness, and high throughput, which enable the fabrication of high‐performance low‐cost electronics . The presence of oxygen vacancies and the valence fluctuation (Fe 2+ /Fe 3+ ) are believed as main factors for the large electrical leakage in the BFO thin film fabricated via a CSD method .…”