Spelling suggestions: "subject:"metalsemiconductor junction"" "subject:"metalsemiconducteur junction""
1 |
Bottom-Up Fabrication and Characterization of DNA Origami-Templated Electronic NanomaterialsAryal, Basu Ram 21 June 2021 (has links)
This work presents the bottom-up fabrication of DNA origami-assembled metal nanowires and metal-semiconductor junctions, and their electrical characterization. Integration of metal and semiconductor nanomaterials into prescribed sites on self-assembled DNA origami has facilitated the fabrication of electronic nanomaterials, whereas use of conventional tools in their characterization combines bottom-up and top-down technologies. To expand the contemporary DNA-based nanofabrication into nanoelectronics, I performed site-specific metallization of DNA origami to create arbitrarily arranged gold nanostructures. I reported improved yields and conductivity measurements for Au nanowires created on DNA origami tile substrates. I measured the conductivity of C-shaped Au nanowires created on DNA tiles (∼130 nm long, 10 nm diameter, and 40 nm spacing between measurement points) with a four-point measurement technique which revealed the resistivity of the gold nanowires was as low as 4.24 × 10-5 Ω m. Next, I fabricated DNA origami-templated metal-semiconductor junctions and performed electrical characterization. Au and Te nanorods were attached to DNA origami in an alternating fashion. Electroless gold plating was used to create nanoscale metal--semiconductor interfaces by filling the gaps between Au and Te nanorods. Two-point electrical characterization indicated that the Au--Te--Au junctions were electrically connected, with non-linear current--voltage curves. Finally, I formed metal-semiconductor nanowires on DNA origami by annealing polymer-encased nanorods. Polymer-coated Au and Te nanorods pre-attached to ribbon-shaped DNA origami were annealed at 170°C for 2 min. Gold migration occurred onto Te nanorods during annealing and established electrically continuous interfaces to give Au/Te nanowires. Electrical characterization of these Au/Te/Au assemblies revealed both nonlinear current-voltage curves and linear plots that are explained. The creation of electronic nanomaterials such as metal nanowires and metal-semiconductor junctions on DNA origami with multiple techniques advances DNA nanofabrication as a promising path toward future bottom-up fabrication of nanoelectronics.
|
2 |
Supraconductivité induite dans le graphène dopé par des nanoparticules métalliques / Superconductvity in Graphene doped by metallic nanoparticlesAllain, Adrien 14 December 2012 (has links)
Cette thèse présente une étude des propriétés de transport à basses températures de matériaux hybrides composés de nano-clusters de métaux supraconducteurs (Sn et Pb) auto-assemblés à la surface d'une feuille de graphène. L'auto-assemblage du métal réalise un réseau bi-dimensionnel désordonné de jonctions Josephson. La caractérisation des propriétés supraconductrices révèle une transition de type 'BKT' avec une température de transition dépendant de la morphologie de la surface. Les propriétés supraconductrices de ce système sont fortement influencées par la grille arrière, qui contrôle la résistance dans l'état normal du graphène. Le résultat le plus marquant de cette thèse a été obtenu en utilisant du graphène désordonné. La présence de défauts structuraux dans la maille de graphène induit un régime de localisation forte à basses températures. En faisant varier le voltage de grille, la résistance de tels échantillons peut varier de 3 ordres de grandeurs. Cette grande dynamique a été mise à contribution pour la réalisation d'une transition de phase supraconducteur-isolant dans des échantillons décorés à l'étain. L'étude de cette transition de phase quantique révèle un comportement de type percolatif et une résistivité universelle prédite par la théorie à la transition. Enfin, un travail préliminaire visant à réaliser des résonateurs mécaniques supraconducteurs à l'aide des ces matériaux hybrides est également présenté. / This thesis presents a study of the low temperature transport properties of hybrid materials made of superconducting metals (Sn and Pb) nano-clusters self-assembled onto the surface of a graphene sheet. The self-assembly realizes a two-dimensional disordered array of Josephson junctions. Characterization of the superconducting properties reveals a transition of the 'BKT' kind, with a transition temperature that depends on surface morphology. The superconducting properties are strongly affected by the gate voltage, which controls the normal state resistance of the graphene sheet. The main result of this thesis was obtained using disordered graphene. The presence of structural defects in the graphene lattice induces a regime of strong localization at low temperatures. Upon varying the gate voltage, the resistance of such samples can change by 3 orders of magnitude. Taking advantage of the large dynamics offered by the gate voltage, we have induced a superconductor-insulator transition in Sn-decorated samples. The study of that quantum phase transition reveals a percolating behavior near the threshold and the universal value of resistivity predicted by theory at the transition. Finally, a preliminary work aiming at using such an hybrid material to realize superconducting nano-electro-mechanical resonators is presented.
|
Page generated in 0.133 seconds