Study On The Growth Of Bi₂Se₃ Topological Insulator Nanodevices And The Transport Properties Of Surface States

With the development of electronic systems to the direction of miniaturization and high reliability,integration has become an inevitable trend,and also brings many probiems like large power consumption,poor heat dissipation and slow running.using new materials to solve these problems is a hot topic in this field.Bi2Se3 topological insulator(TI)is a novel quantum material with an insulating bulk band and gapless metallic surface states that are protected by time-reversal symmetry,In these materials,surface states show large spin-orbit coupling(SOC),and are protected against any time reversal perturbations,such as crystal defects and back scattering.These unique properties make it promising in spin electronics and quantum information,and the development of these two areas will likely have a revolutionary impact on information technology.Achieving controlled growth of topological insulator nanomaterials has very important significance for studying quantum states and nanometer devices.In this paper,we report on the growth of undoped Bi2Se3 nanowires and Bi2(Se1-xTex)3 nanowires and various morphologies Nanosheets by chemical vapor deposition(CVD).By controlling the temperature,carrier gas flow and other related growth parameters we study the electronic transport properties of surface states in Bi2Se3 and Bi2(Se1-xTex)3 nanowires by low-temperature magnetotransport measurement.The main results in our paper include the following aspects:(1)Bi2Se3 nanowires were successfully fabricated by vapor-liquid-solid(VLS)growth method.The diameter of Bi2Se3 nanowires was about 100 nm and the length was 20?30 ?m.Bi2Se3 nanopiates were successfully syntresized via vapor-solid(VS)growth method which showed triangular and hexagonal regular shapes mostly,and the size was about 2?3 ?m.By controlling the growth,substrate temperature,carrier gas flow and other growth parameters,thinner nanowires and nanoplates can be obtained.(2)We report on the electronic transport properties of surface states in Bi2Se3 and Bi2(Se1-xTex)3 nanometer devices under deep low temperature and strong magnetic field,were successfully synthesized by electron beam lithography(EBL)technique,and weak antilocalization(WAL)effect was found,suggesting strong spin-orbit coupling in our nanowire device.It is indicated that the bulk effect can be suppressed effectively by the Tellurium(Te)doping.By fitting the magnetoconductance curves measured in different temperatures,the extracted dephasing length lp decreases from 389 nm in 1.5 K to 39 nm in 20 K,which can be well described by the power law l?? T-0.96.It can be reasonably deduced that both the electron-electron scattering and the electron-phonon scattering play important roles in the Te-doped sample.