Photoelectric Characteristics Of Perovskite Oxide Interface LaAlO₃/SrTiO₃

In this thesis,perovskite oxide interfaces LaAlO₃/SrTiO₃?LAO/STO?are fabricated using pulsed laser deposition?PLD?technique.The TiO₂-terminated STO?001?and 20 degree tilted STO?001?are used as substrates.All-optical wavelength photoelectric properties of the interfaces and the interaction among electric field,light field and magnetic field in the interfaces are investigated.The main research results are listed as follows:1.Several different thickness of LAO/STO interfaces with two types STO?001?substrates are grown by PLD.The temperature dependence of the n-type LAO/STO interfaces resistance is observed,a post-annealing procedure in an oxygen atmosphere can transform the transport property from metallic state into insulating state.The oxygen vacancies in the STO substrate are corresponding for this transition.In addition,thus oxygen vacancies could be tuning or seeding the magnetism rather than inducing magnetism in the LAO/STO interface below 170 K,the spin polarization of Ti3d?t2g?states in the STO substrate plays main role in the magnetism.2.The photoconduction of different thickness n-type LAO/STO interfaces has been investigated under irradiation of solar spectrum at room temperature.The solar spectrum switching characteristic in the interface and the changing trend of photon induced resistance have been observed.The results demonstrate that the interface photoconductive property origins from optical excitation.3.Solar blind ultraviolet lateral photovoltaic effect has been discovered in a 10 uc LAO/STO interface with 20 degree tilted STO?001?substrate at room temperature.The origin of this photovoltaic effect at the interface is mainly from optical excitation and tilted structure.In addition,the oxygen vacancies and defect in the interface have important effects on the lateral photovoltaic effect.The photovoltage peak value is modulated by the irradiation position,and the relative variation is up to 245%.4.The magnetic field enhances spectral response of the 7 uc n-type LAO/STO interfaces is observed in the mid-infrared band when the temperature below 110 K.The mid-infrared spectral response at the interface is mainly from the spin-orbit coupling effect.In addition,the transition of mid-infrared spectral response in the interface is related to the crystallographic phase transition in STO substrate.Meanwhile,two-dimensional IR correlation spectroscopy have been used to investigate the subband structure in the interface,it indicates that the spin-orbit coupling effect play a main role for the mid-infrared spectral response in the interface.5.Terahertz time-domain spectroscopy?THz-TDS?technology has been used to investigate the polar structure and roughness of different thickness n-type LAO/STO interfaces.The phenomenon of strong terahertz reflection in the LAO/STO interfaces has been observed.The results demonstrate that Terahertz radiation have potential applications in detecting the samples with changing polarization and distinguishing the nano-scale thickness in multilayer samples.