离子注入制备BiFeO3/ZnO/graphene多铁性器件

We propose to fabricate graphene-based multiferroic field effect transistors (FETs) using negative cluster beams of C10 produced by the cesium sputtering ion source of a tandetron accelerator. The graphene layer will be directly formed on SiO2, without transfer, by cluster ion implnatation into Ni/SiO2 followed by removal of the Ni layer. The structure and physical properties of the graphene layers will be measured by Raman scattering, HRTEM, AFM, and Hall effect, and the preparation process will be optimized. Then ZnO and BiFeO3 layers will be prepared on graphene by hydrothermal deposition and sol gel method, respectively. The BiFeO3 layer will be in situ doped with rare earth elements and implanted with O ions to increases its magnetization and reduce its leakage current, respectivel. The BiFeO3/ZnO layer will be characterized by ferroelectric and magnetic measurements. Under optimized conditions, a multiferroic FET with BiFeO3/ZnO/graphene/SiO2 structure will be fabricated. The source-drain resistance as a function of gate voltage will be measured and the influence of the electric dipole polorization and magnetization will be systematically studied. This project will lay the base for application of ion beam technology in fabrication of multibit memory based on ultrathin layers of graphene.

用串列加速器的铯溅射离子源产生C10团簇负离子束，注入Ni/SiO2/Si，辅以退火、等离子体刻蚀及化学腐蚀，除去Ni表面graphene和Ni膜，在SiO2表面直接形成graphene，然后沉积BiFeO3/ZnO，制成BiFeO3/ZnO/graphene/SiO2铁电铁磁性场效应管。用Raman光谱、HRTEM、AFM和Hall效应分别测定石墨烯的结构、形貌和载流子特性。ZnO用水热法生长，BiFeO3用溶胶凝胶法生长，并原位掺入稀土元素以增强铁磁性，补充注入O离子以降低漏电流，测定其电滞回线和磁滞回线。系统研究工艺参数对薄膜结构和性能的影响，在优化条件下制备FET器件，测定其源-漏极电阻-栅压曲线及界面特性，利用多铁性膜层的自发电极化和磁化场调控器件的电阻-栅压曲线，实现三比特存储，为离子束技术制备graphene多比特存储器提供科学依据。

BiFeO3（BFO）作为在室温条件下同时具有铁电性和铁磁性的少数材料之一，具有较强的铁电性与磁性耦合相互作用，这种材料在电场作用下诱导的磁化、在磁场作用下诱导的电极化具有线性耦合行为，BFO在双态和四态存储器、自旋电子器件、磁电传感器、磁电开关和调制解调器等方面有应用前景，本项目用离子束方法制备graphene/BFO结构，利用石墨烯的高迁移率尝试制备多铁性快电子器件。首先用离子束方法制备了单层和少层石墨烯，然后用水溶肥制备了ZnO薄膜；用溶胶凝胶法制备了BFO薄膜，并对BFO进行了稀土Pr、La掺杂，对其晶体结构、铁电铁磁性和超精细结构进行了系统的研究，测定了材料的磁学参数和电极化参数，并发展了薄膜超精细结构测量的内转换电子穆斯堡尔谱技术。最后，用超声震荡离心法制备了MoS2二维材料，并试制了Au/MoS2忆阻器，观察到明显的高低阻态开关效应，并在光激发条件下观察到光生忆阻效应，二者结合实现了4比特存储。