Preparation And Electrical Properties Of AlO_x-based Tunnel Junctions

Based on the electronic components,the discovery of the tunnel junction is extremely important in both theory and experiment.The tunnel junction uses the tunnel effect in quantum mechanics as its working principle,and plays a pivotal role in core components such as superconducting electronics,spintronics and semiconductor-based electronics.At the same time,the physical principle of tunnel effect is used as a technical means to provide a powerful experimental tool in the scientific research of detecting the superconducting energy gap,studying the symmetry of superconducting pairing mechanism,and the degree of spin polarization of magnetic materials.The basic structural unit of the metal tunnel junction is a sandwich structure,that is,a metal（M）/tunneling insulating layer（I）/metal（M）structure.According to the principles of quantum mechanics,tunneling the insulating layer is the most critical factor to achieve the tunneling effect.Common insulating barrier layers are:aluminum oxide,magnesium oxide,hafnium dioxide,etc.Among them,alumina is widely used in experiments because of its advantages such as good compactness,high flatness and easy availability.The preparation process of the insulating barrier layer is extremely demanding on the experiment and requires long-term experiment.This paper mainly introduces the growth preparation and physical property characterization of AlO_xinsulating barrier layer.The quality of the barrier layer is determined by the tunnel spectrum test results of Au/AlO_x/Pb（Al）planar junction.The main content and structure of this paper are as follows:Chapter 1 Introduction.It mainly introduces the research background and significance of tunnel junction preparation.Chapter 2 Introduction of thin film preparation characterization and test equipment.It mainly introduces the related instruments and main experimental materials used in the preparation,characterization and testing of Au/AlO_x/Pb（Al）planar junctions.Chapter 3 Exploration on the preparation process of Au/AlO_x/S.The exploration process of the tunnel junction preparation process is elaborated in detail,including the preparation of the Cr/Au bottom electrode,the preparation of the AlO_xinsulating barrier layer,and the preparation of the Pb（Al）top electrode.Chapter 4 Plane junction low temperature transport measurement.The Au/AlO_x/Pb（Al）planar junction tunneling spectrum measurement at low temperature is introduced in detail,and the quality of the AlO_xbarrier layer is judged by the tunneling spectrum to determine the relevant parameters of the preparation process.Chapter 5 Application of AlO_xoxidation process to other materials.A brief introduction to the related trial work using tunnel junctions on Fe₃Ge Te₂and（Ba,K）（Zn,Mn）₂As₂materials.