Reasearch On The Fabrication Of BiFeO₃ Thin Films For RRAM Application

The resistive random access memory?RRAM?has supposed to be the most promising candidate for novel non-volatile memory?NVM?devices due to its advantages,including the high-speed operation,high-density integration,and semiconductor process flow compatibility.BiFeO₃ based RRAM is one of the most promising resistive memory devices with the characteristics of stable performance,low read/write operation voltage.So far,many scientist have already widely studied BFO thin films fabricated by pulsed laser deposition?PLD?and sol-gel method.However,the resistive switching effect in BFO thin films grown by radio frequency?RF?magnetron sputter is related limited.In this paper we successfully fabricated BFO based RRAM device by RF magnetron sputter,and then interpret its characters by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Atomic force microscope?AFM?,ferroelectric tester and semiconductor analyzer,Our work in this paper can be briefly summarized in the follow:Firstly,the Pt/BiFeO3/Nb:SrTiO3/In heterostructure were successfully grown on the Nb:SrTiO₃?001?substrate by RF Magnetron sputter at room temperature.The I-V curves normally showed the bipolar resistive switching effect in the device.The resistance switching ratio between HRS and LRS was more than 200 and it exhibited excellent retention characteristic over 3600 s.The conduction mechanism complied with the trap-controlled SCL conduction.The resistive switching effect of the structure was attributed to the change of the BFO/NSTO interface barrier height as a result of the defect center?oxygen vacancy?trapping/detrapping process.Secondly,we investigated the influence of annealing pressure on resistive switching effect.It is found that low annealing pressure will increase the oxygen vacancy content and even reverse the resistive switching direction of the Pt/BiFeO3/Nb:SrTiO3/In heterostructure.Thirdly,By optimizing the deposition parameters,we successfully fabricated the Au/Bi FeO₃/SrRuO₃/SrTiO₃ device on SrTiO₃?001?substrate by RF magnetron sputter.The high-quality crystalline BFO and SRO thin films is proved by XRD,SEM test.The device performs good ferroelectric properties and bipolar resistive switching effects.The resistive switching effect of the structure was attributed to the Schottky barrier in Au/BiFeO₃ interface.