| Due to the strong coupling between electrons,orbits,spins and lattices in perovskite transition metal oxide,there will be many rich and strange properties,such as high temperature superconductivity,colossal magnetoresistance effect and interface two-dimensional electron gas(2DEG)and so on,which inspired people's enthusiasm for the study of perovskite transition metal oxide materials.Because of spin-orbit interactions and electron-electron interactions in 4d perovskite transition metal oxides,many novel properties have appeared,such as unconventional superconductors in Sr2RuO4.LaRhO3(LRO)is a typical 4d perovskite transition metal oxides,which is paramagnetic semiconductor and shows excellent catalytic and thermoelectric performance.Thin film has more advantages than bulk.From an application point of view,compared to bulk materials,thin films are more conducive to the miniaturization and integration of devices than the bulk material;from the perspective of physical research,thin films will have new phenomena that are different from bulk materials,which are worthy of further exploration.In this work,we found the growth window of the LRO film using pulsed laser deposition(PLD),and then studied its transport research in different environments.This work not only enriches and deepens the understanding of 4d perovskite transition metal oxide materials,but lay the foundation for future device preparation.The content of this paper is divided into six chapters:The first chapter summarizes the basic knowledge and background of perovskite transition metal oxide materials,then introduces the research progress of 4d rhodium oxide,and finally introduces the property changes and mechanism research of perovskite transition metal oxide materials under light and atmosphere.The second chapter introduces the growth process,characterization method of the epitaxial film and self-build system in detail.The third chapter is to study the influence of different growth parameters on LRO thin film and the basic physical properties of LRO thin film.The effect of different growth parameters on LRO thin film is systematically studied.The growth phase diagram of the LRO film is found,which is important for the subsequent property control.And the basic properties of LRO thin film,such as magnetic,electrical and spectral properties,were studied.The fourth chapter is to study the transport properties of LRO films under different light wavelengths.According to the LRO film growth window found in Chapter 3,high-quality LRO film was grown on the STO(110)substrate.The transient photoconductance(TPC)of the LRO film was systematically studied under different laser wavelengths and powers.The laser wavelength is shortened,and the TPC effect of the LRO film is enhanced under the same power.The laser power is increased,and the TPC effect of the LRO film is linearly enhanced under the same laser wavelength.The TPC of the LRO film decreases significantly during on the surface of the LRO thin film,indicating that the thermal effect accounts for an important part of the TPC effect of the LRO film,because flowing air will increase the heat dissipation.This work will contribute to synthesize the optoelectronic devices using LRO thin films.The fifth chapter is to study the electric transport of LRO film under different volatile organic gases.After testing a variety of organic gases,it is found that the LRO film has the highest response to ethanol.After gold modification,the gas sensitivity of the LRO film is significantly improved.X-ray photoelectron spectroscopy(XPS)analysis,the ratio of adsorbed oxygen of gold decorated LRO film increases greatly.Because the adsorbed oxygen and ethanol molecules undergo redox reactions,it will result that the gas sensitivity of the LRO film after Au modification is significantly improved.It is an effective way using gold to decorate the perovskite transition metal oxide film to improve its gas sensitivity,which lays a theoretical foundation for the preparation of LRO film gas sensors.The sixth chapter summarizes the thesis and some future works.Firstly,ultrafast optics is an effective way to study the ultrafast dynamics process in materials.However,the ultrafast dynamics process of LRO films is not yet clear.It is important for the research on ultrafast optics of LRO films.And it will provide a theoretical basis for the realization of ultrafast devices in the future.Secondly,the electric field can control the properties of the film effectively.Therefore,the research of LRO thin film under electric field is meaningful. |
PDF Full Text Request