Magnetoresistance And Electro-resistance Effects In Magnetic Heterojunctions

Information and communication technology is the symbol of information age, which penetrates to all aspects of life. In this day and age, data storage not only becomes increasingly important but also takes a huge market share and is closely related to our daily life. Transistor based traditional process has encountered a development bottleneck due to its decreasing feature size. People have paid many attentions to the research of new generation of memory because of its simple structure and long time data retention. For all those memory, The unit cell of MRAM and RRAM with a simple MIM(metal-insulatormetal,)“sandwich” structure have lots of advantages, for example, high storage density, fast reading and writing speed, scalability from non-charge storage mechanism, submicron-sized layer structure properties, repeatability and CMOS compatibility. As a result, it has become a current hot spot.In this paper, magnetic tunnel junctions(MTJs) on silicon substrates and RS unit were fabricated using in situ shadow-masks. We use XRD, XPS, AFM and currentvoltage sourcemeter instrument to analyze the film structural components, surface morphology and transmission properties. The main idea is as follows:(1) Fully epitaxial Fe Co/Mg O/Fe magnetic tunnel junctions on silicon substrates were fabricated using in situ shadow-masks in an electron-beam deposition system. An inverse tunneling magnetoresistance(TMR) of-39% was observed at 77 K after annealing, which was not obtained in MTJs grown in better vacuum with the same device structure. This inverse TMR is attributed to the oxidation of the Fe Co/Mg O interface, which provides a negative spin polarization. Then improving the vacuum by adding a liquid nitrogen cooled shroud about 5×10-10 torr, room temperature magnetoresistance was 50% and gradually increased to 92%with decreasing temperature to 77 K. After annealing, we found normal positive TMR increased both at RT or at 77 K.(2)Using Pulse laser deposition system deposits n-Si/Si O2-Co Fe2O4/In resistance switching units, We studied the process of its growth temperature, oxygen partial pressure, whether keep the pressure after depositing, and the thickness of the insulating layer, then we take the most of optimal growth parameters: 1.6Pa oxygen partial pressure,700 ? and film thickness of 8 nm we obtain the resistance switching unit with bipolar resistance switch features, then analyzed its conductive mechanism preliminarily.