Study On The Rectifying Effect In Nb:SrTiO₃/ZnO Epitaxial Heterojuntion

It is an informational society today.. Along with the rapid development of network and a variety of electronic products, more and more people eager for new material to improve the current status of single material, thus more researchers plan and carry out the relevant research work of various heterostucture.Zn O as a group II-VI compounds with a direct wide bandgap?3.3 eV? of hexagonal wurtzite structure semiconductor. It has a high exciton binding energy and transparent conductive, so it has broad application in blue and ultraviolet light-emitting devices, photovoltaic devices, diluted magnetic semiconductors and transparent conductive materials. SrTiO₃?STO? single crystal with a perovskite structure is often used to epitaxially grow functional oxide films, Zn O and Nb:SrTiO₃?NSTO? epitaxial heterostructures have been found to exhibit resistive switching and negative differential resistance, and for the heterojunction of ZnO nanorods on NSTO, the electronic properties are found to be drastically reconfigured by applying voltage and light, thus attracting more and more attention. In addition, the magnetic properties of non-magnetic element heterojuntion have become a research hotpot in recent years, especially the two non-magnetic oxide dielectric interface has produced an interesting epitaxial heterostructure, has been discovered to present ferromagnetism and superconductivity, or coexistence of ferromagnetism and superconductivity.Especially, magnetic field modulated electrical transport phenomena in nonmagnetic oxide heterostructures is attracting much attention because of its broad application prospects. For example, magnetoresistance can be used in giant magnetoresistance sensors and magnetoresistive random access memory.ZnO thin films were fabricated on 0.7% Nb-SrTiO₃ single crystal substrate using the magnetron sputtering technique. XRD ?-2? and ? scanning results show epitaxial growth of ZnO films on NSTO single crystal substrates. The top electrode Au and bottom electrode In both ohmic contacts were fabricated to form the Au/ZnO/NSTO/In devices. The current-voltage curves show good rectifying characteristics. When we apply a magnetic field to the sample, the rectification ratio increases. This is supposed to be related to the interfacestate density of NSTO/ZnO heterojuntion. Electrical properties of NSTO/ZnO heterojunction we studied under variable temperatures, the ideality factor, barrier height, rectifying ratio, the interface state density are found to exhibit similar behavior after applying a magnetic field at different temperature, indicating that NSTO/ZnO heterojunction at each temperature will be affected by the magnetic field. The hysteresis loop?M-H? curves measured by physical properties measurement system?PPMS? show that magnetic field severely affected NSTO/ZnO heterojunction interface. So how magnetic field affected the interface state, the strength of the magnetic field changes if will change the interface state, and the different magnetic field direction how effects on the interface state, these all we need to research, and this is an important part in our next work.In addition, we also use deep level transient spectroscopy?DLTS? techniques to detect deep-level defects of NSTO/ZnO heterojunction. From the energy level and capture cross-section, interface state and deep level defects are found to be present at the NSTO/ZnO heterojuntion interface. The next step of research, we can also study the impact of the magnetic field on the deep level defects in NSTO/ZnO heterostrcture.