The Heterojunction Preparation And Electrode Contact Properties Of Bi₂Se₃ Topological Insulator

Since the topological insulators have been predicted and prepared, their unique physical properties have been drawn great attention by scientists, and lead to a great upsurge of research. After years of research, the second generation of three-dimensional topological insulator Bi2Se3 because of its surface only one Dirac cone and a series of novel physical properties, opened a new chapter for the study of topological insulator. A lot of scientific researches show that Bi2Se3 doped with magnetic elements will change its transport characteristics,and when the thickness of the prepared fi2Se3 lms is less than 7nm,its surface state of upper and lower surface will influence each other, causing more exotic electric transport properties.Therefore,this topological insulator Bi2Se3 heterojunction sample is prepared by molecular beam epitaxy (MBE) in this experiment. The interaction surface effect of Bi2Se3 heterostructure will be analyzed through the comparison of the Bi2Se3 heterojunction and Bi2Se3 single crystal electrical properties. The surface of Bi2Se3 single crystal appears various of defects easily. The surface of Bi2Se3 single crystal appears various of defects easily, so selecting different conditions to prepare optimize samples, and using the XRD and SEM test tool to obtain the best preparation parameters, to optimizing the parameters of preparation of Bi2Se3 heterojunction sample. The test of Bi2Se3 single crystal and heterojunction metal target samples need to select high-quality contact characteristics as the target, to avoid possible Schottky barrier, so the electrode is prepared by different work functions metal target evaporate in Bi2Se3 single crystal surface,the best contact metal targets can be obtained by testing the T-1 curve of metal targets, the optimum metal target evaporates in the surface of Bi2Se3 single crystal and the heterostructure sample surface as the target electrode,compare and analysis the electrical properties of them.The results indicate that Bi and Se flow ratio is 1:10 as the optimal preparation parameters, and In is the most suitable metal as target electrode. The magnetoresistance of Bi2Se3 heterojunction samples is higher than Bi2Se3 crystal,and the system carrier changes curiously.