000232434 001__ 232434
000232434 005__ 20190619041447.0
000232434 0247_ $$2doi$$a10.5075/epfl-thesis-7939
000232434 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis7939-3
000232434 02471 $$2nebis$$a11072241
000232434 037__ $$aTHESIS
000232434 041__ $$aeng
000232434 088__ $$a7939
000232434 245__ $$bGrowth, Structural & Electrical Properties$$aGold-free Growth of InAs Nanowires
000232434 260__ $$bEPFL$$c2017$$aLausanne
000232434 269__ $$a2017
000232434 300__ $$a155
000232434 336__ $$aTheses
000232434 502__ $$aprofesseure Cécile Hébert (présidente) ; Prof. Anna Fontcuberta i Morral (directeur de thèse) ; Prof. Nicolas Grandjean, Prof. Paul C. McIntyre, Prof. Kimberly Dick Thelander (rapporteurs)
000232434 520__ $$aSemiconductor nanowires are interesting building blocks for a variety of electronic and optoelectronic applications, and they provide an excellent platformto probe fundamental physical effects. For the realization of nanowire based devices, a deep understanding of the growth mechanism and the nanowire properties is required. In this thesis we investigate gold-free growth of InAs(Sb) nanowires and their properties. Nanowires are grown by molecular beam epitaxy on GaAs(111)B substrates. In the first part of this thesis we demonstrate the growth of InAs and InAs1¡xSbx nanowires and show that polytypism can be suppressed by the incorporation of antimony. The electric properties of InAs(Sb) nanowires are studied by electrical measurements and by Raman spectroscopy, and a higher electron mobility is found for defect-free InAs0.65Sb0.35 nanowires compared to InAs nanowires. We also investigate surface passivation using aluminiumoxide. The oxide layer not only serves as passivation layer but it can also be used as gate-dielectric for top-gated field-effect devices. The second part of this thesis is dedicated to the nanowire growth direction and orientation with respect to the substrate. We analyze the existence of tilted nanowires on (111)B substrates, and demonstrate that in most cases they are a result of 3D twinning at the early stages of growth. In addition, also a few unconventional crystalline directions are observed. The ratio of tilted nanowires can be tuned by the growth conditions and substrate preparation. This allows to achieve either all vertical nanowires or a high density of tilted nanowires, whichever is desired for a certain application. Our results also shed light upon the growth mechanism of InAs nanowires, since 3D twinning is associated with the presence of a droplet. Being able to control the formation of tilted nanowires is important, but for certain applications it is also desired to modify the growth direction during growth. For example topological qubits based onMajorana Fermions require junctions and networks. In the third part of this thesis we show a new approach to change growth direction. For this, InAs nanowires are annealed in vacuum in order to create indium droplets. The droplets first formon the top facet of the nanowires and then slide down onto the nanowire side facets. These droplets can act as catalyst-particle, and re-initiation of growth results in L-shaped nanostructures. Merging of these nanostructures constitutes a new approach for the formation of nanowire networks.
000232434 6531_ $$aIII-V semiconductors
000232434 6531_ $$ananowires
000232434 6531_ $$amolecular beam epitaxy
000232434 6531_ $$acrystal structure
000232434 6531_ $$apolytypism
000232434 6531_ $$atwinning
000232434 6531_ $$agrowth direction
000232434 6531_ $$asurface passivation
000232434 6531_ $$aatomic layer deposition
000232434 6531_ $$aelectrical properties
000232434 700__ $$0247654$$g234668$$aPotts, Heidi Andrea
000232434 720_2 $$aFontcuberta i Morral, Anna$$edir.$$g182447$$0243742
000232434 8564_ $$uhttps://infoscience.epfl.ch/record/232434/files/EPFL_TH7939.pdf$$zn/a$$s45418212$$yn/a
000232434 909C0 $$xU11832$$0252277$$pLMSC
000232434 909CO $$pthesis-bn2018$$pthesis-public$$pDOI$$ooai:infoscience.tind.io:232434$$qGLOBAL_SET$$pSTI$$pthesis$$qDOI2
000232434 917Z8 $$x108898
000232434 917Z8 $$x108898
000232434 918__ $$dEDMX$$cIMX$$aSTI
000232434 919__ $$aLMSC
000232434 920__ $$b2017$$a2017-11-24
000232434 970__ $$a7939/THESES
000232434 973__ $$sPUBLISHED$$aEPFL
000232434 980__ $$aTHESIS