TY  - JOUR
A1  - Sacépé, Benjamin
A1  - Oostinga, Jeroen B.
A1  - Li, Jian
A1  - Ubaldini, Alberto
A1  - Couto, Nuno J. G.
A1  - Giannini, Enrico
A1  - Morpurgo, Alberto F.
T1  - Gate-tuned normal and superconducting transport at the surface of a topological insulator
JF  - Nature Communications
N2  - Three-dimensional topological insulators are characterized by the presence of a bandgap in their bulk and gapless Dirac fermions at their surfaces. New physical phenomena originating from the presence of the Dirac fermions are predicted to occur, and to be experimentally accessible via transport measurements in suitably designed electronic devices. Here we study transport through superconducting junctions fabricated on thin Bi2Se3 single crystals, equipped with a gate electrode. In the presence of perpendicular magnetic field B, sweeping the gate voltage enables us to observe the filling of the Dirac fermion Landau levels, whose character evolves continuously from electron- to hole-like. When B=0, a supercurrent appears, whose magnitude can be gate tuned, and is minimum at the charge neutrality point determined from the Landau level filling. Our results demonstrate how gated nano-electronic devices give control over normal and superconducting transport of Dirac fermions at an individual surface of a three-dimensional topological insulators.
KW  - Physical sciences
KW  - Condensed matter
KW  - Materials science
KW  - nanotechnology
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-140175
VL  - 2
ER  - 
TY  - THES
A1  - Göpfert, Sebastian
T1  - Einzel-Quantenpunkt-Speichertransistor: Experiment und Modellierung
T1  - Single quantum dot memory transistor: Experiment and modeling
N2  - In dieser Arbeit wurden Einzel-Quantenpunkt-Speichertransistoren im Experiment untersucht und wesentliche Ergebnisse durch Modellierung nachgebildet. Der Einzel-Quantenpunkt-Speichertransistor ist ein Bauelement, welches durch eine neuartige Verfahrensweise im Schichtaufbau und bei der Strukturierung realisiert wurde. Hierbei sind vor allem zwei Teilschritte hervorzuheben: Zum einen wurde das Speicherelement aus positionskontrolliert gewachsenen InAs Quantenpunkten gebildet. Zum anderen wurden durch eine spezielle Trockenätztechnik schmale Ätzstrukturen erzeugt, welche sehr präzise an der lateralen Position der Quantenpunkte ausgerichtet war. Durch diese Verfahrensweise war es somit möglich, Transistorstrukturen mit einzelnen Quantenpunkten an den charakteristischen Engstellen des Kanals zu realisieren.
N2  - In this thesis single-quantum-dot memory-transistors have been studied in experiment and the experimental findings have been reproduced by modeling. The studied single-quantum-dot memory transistor is a device which has been realized by a novel process technique as regards layer composition and structuring. According to this there are two steps to be emphasized: First the memory element is based on site-controlled grown InAs quantum dots. Second, there has been used a unique dry etching technique to define narrow etched structures, which have been precisely aligned laterally with respect to the position of the quantum dots. Due to this method it was possible to realize transistor structures with single quantum dots centered in a quantum wire.
KW  - Quantenpunkt
KW  - Transistor
KW  - Speicherelement
KW  - single electron transport
KW  - single quantum dot
KW  - nanotechnology
KW  - Nanotechnologie
KW  - Elektronischer Transport
KW  - Single electron transfer
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-80600
ER  -