Investigation Of Structural And Physical Properties Of BiFeO₃ Based Epitaxial Film Heterostructure

BiFeO₃?BFO?of room temperature ferroelectricity and antiferromagnetic properties,has broad applications in data storage,magnetoelectric devices and microelectronic devices.We used off-axis RF magnetron sputtering to prepare BFO heterostructures with different orientations.Various technical methods were used to study the physical properties of samples,including resistive change,ferroelectric properties.Main results are listed as follows.?1?The Pt/BFO/LSCO(La_0.5Sr_0.5CoO₃)heterostructure was constructed on a SrTiO₃?STO??00l?oriented substrate using off-axis RF magnetron sputtering.X-ray diffraction results indicate that the BFO film is epitaxial and it is well crystalinized.A good butterfly-shaped measured at 5 V indicates excellent ferroelectricity.Under positive and negative voltages,the resistance states show a transition from high resistance state to low resistance state,indicating diode resistance switching behavior.The logarithm of the I-V curve is fitted.When the forward voltage is 0?5?0 V and the negative voltage is 0?-5 V,the slope S is S¹,S² and S>>2,which is in accordance with the space charge limiting current?SCLC?conduction mechanism.?2?The Pt/BFO/LSCO heterostructures were fabricated on three oriented STO substrates using off-axis RF magnetron sputtering.Epitaxial BFO films with different orientations were obtained,and they were well crystalinized.The C-V and I-V curves of the three oriented film heterostructures were tested at 5 V.The results show that the BFO?110?film has the highest dielectric constant and the BFO?001?film has the lowest dielectric constant;Under the forward voltage 0?5?0 V,the resistance state changes from high resistance state to low resistance state.Under the negative voltage 0?-5?0 V,the resistance state changes from low resistance state to high resistance.It is a high-impedance state and conforms to the bipolar resistance switching behavior.The logarithmic fitting of the I-V curve shows that the slope S of the three orientation films is S¹,S² and S>>2,and the conduction mechanism is consistent with the SCLC mechanism.?3?The Pt/BFO-0.3BT/LSCO heterostructures were fabricated on STO?00l?substrates by pulsed laser deposition.The effect of growth temperature on structure,dielectric properties and ferroelectricity was studied.Among the five samples at 650°C,675°C,700°C,725°C and 750°C,the crystalinity of the film increases with increasing temperature.At 700°C,it is highly?00l?oriented.C-V and P-V tests show that there is an antiferroelectric phase inside the film.Upon to 750°C,the peaks disappear,the film is epitaxial with very good,dielectric and ferroelectric properties.