MOCVD Growth And Characterization Of GaAs-based Nanowires

The nanowires with GaAs-based materials have received great attention in the past decades,due to their potential applications in the new generation of electronics and optoelectronics.Properties such as high mobility and drift velocity make GaAs-based nanowires appropriate candidates for fabrication of infrared detectors,field effect transistors,infrared lasers,light emitting diodes,solar cells and single photon sources.The devices with nanowires have received more attention than epitaxial growth has,which would provide motivation for device fabrication.Yet,decent performance of photoelectric devices comes with high quality of crystal and morphology.It's obviously vital to obtain the technology to grow GaAs-based nanowires with fine morphology.There're still many diffculties to conquer when high quality nanowires are needed.Phenomenon like kinking and toppling could lead to a barricade in nanowires fabrication.In this paper,three methodes are taken to fabricate GaAs-based nanowires and the distribution,morphology and composition are deeply studied.The main research works are carried out as follows:1?Au-catalyzed GaAs-based nanowires with cylindrical morphology are grown by metal-organic chemical vapor deposition on GaAs(111)B substrates.The impact of film thickness,growth temperature and ?/? ratio are analyzed.GaAs-based nanowires without kinking or toppling are obtained.The geometry of nanowires turns from cylindrical to conoid with growth tempreature increasing.A parabolic trend of nanowire growth rate occurs as ?/? ratio is rising.2?Nanowires heterostructure of GaAs/InGaAs,GaAs/GaInP and GaAs/GaAsP are grown and distinct heterostructure interfaces are observed.Energy dispersive spectrometer are applied to investigate the mechanism of nanowires growth.It's considered that the In atoms prefer to participate the process of growth via substrate surface rather than catalytic droplets,leading to a InGaAs segment at the bottom of a nanowire.3?It takes 700? to grown nanowires with hexagonal prism morphology on selective-area substrates.The growth rate decreases rapidly because of the absence of catalytic droplets.Au-catalyzed GaAs nanowires are fabricated on selective-area substrates via vapor-liquid-solid mechanism.The growth rate is increased obviously after catalytic droplets are induced.