Effect of (Bi,Gd)FeO₃ Layer Thickness on the Microstructure and Electrical Properties of BiFeO₃ Thin Films

Abstract

BiFeO 3 /(Bi,Gd)FeO 3 (BFO/BGFO) bilayered thin films with different BGFO layer thicknesses were grown on SrRuO 3 /Pt/ TiO 2 /SiO 2 /Si(100) substrates using radio frequency sputtering. The grain size of BFO layer changes with the thickness of BGFO layer, and the BGFO layer decreases the leakage current density of BFO. The electrical properties of BFO/BGFO are tailored by changing the BGFO layer thickness. The dielectric constant (e r ) of BFO/BGFO decreases with increasing BGFO layer thickness, owing to a smaller e r value of BGFO. The BFO206/BGFO150 layer has better ferroelectric properties (2P r~1 37.7 lC/cm 2 and 2E c~7 22.0 kV/cm) due to the enhancement in (111) orientation and a denser microstructure. All bilayers have a much better fatigue behavior than that of BFO single layer. Moreover, the fatigue behavior of BFO/BGFO is dependent on the film orientation induced by different BGFO layer thicknesses, and the BFO206/BGFO220 bilayer exhibits a best fatigue endurance due to the (100) orientation. The fatigue mechanisms are illuminated by the frequency-dependent dielectric behavior and the resistivity as well as the leakage behavior before and after fatigue. As a result, the bilayer structure is an effective way to improve the electrical behavior of bismuth ferrite.

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] .…”

“…Electrical and magnetic properties of BFO homojunction multilayersRecently, we have investigated the homostructures of BFO thin films by avoiding the weak (or even zero) ferroelectricity of an additional layer [359][360][361][362][363][364][365]. P r values of ~69.0-94.7 μC/cm 2 were demonstrated.Table 18 shows electrical and magnetic Pt/TiO 2 /SiO 2 /Si substrates by RF sputtering, giving rise to enhanced physical properties (2P r =52.2 C/cm 2 , 2E c =554.0 kV/cm, 2M s =96.0 emu/cm 3 , 2H c =253.2 Oe)…”

Multiferroic and Nanomechanical Properties of Bi1−xGdxFeO3 Polycrystalline Films (x = 0.00–0.15)

“…MF and mechanical characteristics of the Gd-doped BFO bulks and films, which have been developed up to now [33][34][35][36][37], are listed in Table 1. First of all, BGFO bulks exhibit poor ferroelectric and weak ferromagnetic properties.…”

“…First of all, BGFO bulks exhibit poor ferroelectric and weak ferromagnetic properties. Besides, the significant improvement in ferroelectric properties is found for BGFO polycrystalline films, especially for Bi 0.95 Gd 0.05 FeO 3 with the increased 2P r of 90 µC/cm 2 [36]. In general, simultaneously improving ferroelectric and ferromagnetic properties is extremely difficult.…”

Modulating light absorption and multiferroic properties of BiFeO3-based ferroelectric films by the introduction of ZnO layer

“…At 300 kV cm −1 , the leakage current densities of BFO, ZnO/BFO and BFO/ZnO thin films are 2.98×10 -4 A cm −2 , 3.40×10 -5 A cm −2 and 1.30×10 -5 A cm −2 , respectively. Due to the existence of oxygen vacancies and the promoted undulation of Fe 2+ /Fe 3+ valence cause by the electronic instability of the Fe ions, The BFO films present a large leakage current [30,31]. On the contrary, the leakage current densities of ZnO/BFO and BFO/ZnO bilayers were found to be lower than that of the BFO thin film.…”