Abstract
In this work, GaAs nanowires were grown on the GaAs (111)B substrate by molecular beam epitaxy (MBE). First, Au film with a thickness of 1 nm was deposited onto the GaAs (111)B substrate through e-gun evaporation to form metal seeds for further VLS growth of GaAs nanowires. After Au film deposition, the sample was inserted into MBE chamber, heated up to the desired temperature of 600℃ in order to remove the oxide layer and to form droplets of eutectic Au-Ga liquid alloy. After annealing, GaAs nanowires were grown at a substrate temperature of 540 ℃. With various growth parameters, i.e. time, temperature and source BEP, the morphologies of nanowires were changed. Hence, the GaAs nanowire with core- shell structure could be obtained by adjusting different parameters such as Ga, As fluxes and growth temperature. The nanowires were systematically investigated using different instruments. Scanning electron microscope (SEM) demonstrates different morphologies of nanowires. The diameter of nanowires is increasing with increasing Ga flux under a constant As flux, while the axial growth rate is increasing with increasing As flux under a constant Ga flux. From the observation of Transmission electron microscopy (TEM), a great deal of defects, e.g. stacking faults and twins, were found in the nanowires with increasing growth rate. Thus, this growth condition mentioned above resulted in a worse quality of nanowires.