Resistance Detection Method In The Process Of Interface Channel Formation In Al/STO

The quasi-two-dimensional electron gas（Q2DEG）at the AlO_x/SrTiO₃（STO）interface has rich physical properties,such as metal-to-insulator transition,superconducting electricity,magnetism and photosensitivity,and is a hot topic in current research.At room temperature,a layer of Al thin film can be deposited on the surface of SrTiO₃ by electron beam evaporation,which can transform the surface of SrTiO₃ into a metallic state.Compared with epitaxial growth and Ar⁺bombardment,this method has a simpler manufacturing process and does not require heating,making it a current research hotspot.Understanding and controlling the formation of conductive layers at the AlO_x/SrTiO₃ interface is important for adjusting the interface reaction and designing2DEG electronic devices with specific carrier densities,which is not possible with 2DEG in LaAlO₃/SrTiO₃.However,the process of the formation of conductive layer at the AlO_x/SrTiO₃ interface is lacking.Therefore,this thesis uses resistance method to study the formation process of conductive layer at AlO_x/SrTiO₃ interface.The main contents are as follows:1.A resistive method for measuring the natural oxidation of metal Al has been established,and its oxidation results have been found to be consistent with the measurements of natural oxidation of Al thin films obtained using a quartz crystal microbalance（QCM）.The oxidation process of the Al thin films has been analyzed,and the feasibility of this resistive method has been verified.First,the relationship between the resistivity and thickness of the Al film is obtained using the four-point probe method.The resistivity of the Al film,denoted asρ（t）,is then used to correct the resistance method,eliminating the calculation deviation of the oxide layer thickness caused by the size effect of the thin film.Next,the resistance method and the combination of QCM was used to capture the complete natural oxidation process of the Al film.The entire oxidation process results in the formation of an approximately 13 nm thick aluminum oxide layer.Finally,the oxidation kinetics of the Al were discussed.The initial oxidation kinetics of Al follows a logarithmic law,while after three hours,the oxidation kinetics transition into a square law.2.The measurement method for studying the oxidation process of the AlO_x/SrTiO₃interface based on the resistance method was investigated,and the oxidation kinetics were analyzed.The results show that,in a vacuum environment,when the thickness of the Al film was greater than 27 nm and the sheet resistance of the sample was less than 3000Ω/□,the change in resistance was determined by the oxidation of the Al film.At this point,only the oxygen atoms from the Al film react with the SrTiO₃ substrate.Therefore,the formation process of the conducting layer at the AlO_x/SrTiO₃ interface can be inferred by monitoring the oxidation of Al.It was found that a conducting layer with a thickness of approximately 1.5 nm was formed at the interface between Al and SrTiO₃.The oxidation kinetics of the formation process of the conducting layer at the AlO_x/SrTiO₃ interface were analyzed,and it was determined that the oxidation kinetics follow a logarithmic law.The formation of the conducting layer at the interface was mainly achieved through the diffusion of charged particles.3.Finally,electrical characterization tests were conducted on the conducting layer at the AlO_x/SrTiO₃ interface,and the carrier concentration and mobility exhibited electrical properties similar to the two-dimensional electron gas（2DEG）at the LAO/STO interface.In a 4K environment,the sheet resistance of the conducting layer at the AlO_x/SrTiO₃ interface with 10 nm thick Al film was measured to be 365Ω/□.The carrier concentration was determined to be 2.24×10¹³ cm^-2,and the mobility was found to be1000 cm²·V^-1·s^-1.These electrical characteristics were consistent with the reported electrical properties of the AlO_x/SrTiO₃（STO）interface Q2DEG in the literature.