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Elektronenstrahlschreiber

Fachliche Zuordnung Physik der kondensierten Materie
Förderung Förderung in 2010
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 189156649
 
Erstellungsjahr 2015

Zusammenfassung der Projektergebnisse

The usage of the dedicated, state-of-the-art electron-beam writer was directly linked to the research of the DFG-Center for Functional Nanostructures (CFN) which was established by the DFG in 2001 and funded until 2014. The researchers at the interdisciplinary research center worked together in five research areas: Nano-Photonics (Area A), Nano-Electronics (Area B), Molecular Nanostructures (Area C), Nano-Biology (Area D) and Nano-Energy (Area E). In detail, the electron-beam writer was essential to perform following projects: 1. CFN Young Scientist Group Project A2: Semiconductor Epitaxy: Semiconductor quantum dots are conventionally grown in a self-assembly process, the so called Stranski-Krastanov growth mode. This approach is random in nature and if one thinks of scalable applications randomness seems rather inconvenient. That is why researchers have been looking for a way to control the position and size of quantum dots. It was found that small holes on the substrate surface were useful to spatially define nucleation sites where quantum dots would preferentially grow. A successful route to fabricate shallow holes with tens of nanometer dimensions on semiconductor surfaces is electron-beam lithography. This powerful technique was employ to pre-structure GaAs substrates. We then use molecular beam epitaxy to grow site-selective InAs quantum dots. In(Ga)As/GaAs is of particular interest because of its tunability of the bandgap in a technologically interesting range and the long experience with this system. 2. CFN Project A4: Nanophotonic Devices: Another research project was the investigation of hybrid nanophotonic devices. These devices systematically combine waveguides for light made from silicon and plasmonic structure with electro-optical organic materials. For this purpose a wide diversity of nanostructures has been fabricated by electron-beam lithography and downstream etching processes. 3. Erasmus Mundus Program “Europhotonics”/CFN Project A5: Bio-Photonics: In this project the inserting of quantum emitters such as quantum dots and laser dyes into polymeric whispering-gallery resonators with high Q factors was investigated. A modal filtering of the emission from quantum dots and the laser emission of single quantum dots has been observed. Furthermore, an optically induced large tunability of the resonators was achieved by integration of liquid-crystal elastomers. 4. DFG-Emmy Noether Junior Research Group/CFN Project A6: Quantum Nanophotonics: Integrated nanophotonic circuits allow for realizing complex functionality in a chip-scale framework. Because nanophotonic structures are furthermore size-matched to nanomechanical resonators, additional mechanical degrees of freedom can be harnessed for tunable optical devices. Within this project sub-wavelength optical components are realized for applications in optomechanics and on-chip sensing as functional building blocks for hybrid circuits. Through co-integration with nanoscale emitters such a platform enables next-generation optical circuits. 5. CFN Project B3: Superconducting Josephson Devices: Three major research topics have been addressed utilizing the dedicated electron-beam writer: 1. Nano-scale Josephson junctions to study charge transport dynamics in superconducting circuits: The transport characteristics of nanometer sized Josephson junctions are an interesting research field due to the occurrence of dominant single electron effects, as for instance the coulomb blockade of current. High resolution electron beam lithography is here a mandatory requirement for the Josephson junction fabrication. Several samples have been successfully prepared and measured employing the electron beam writer as a key fabrication tool. 2. Nano-scale Josephson junctions for coherent manipulation of superconducting Qubits: Superconducting Qubit circuits based on Josephson junctions are a promising candidate for a scalable quantum computer. One of the key figure of merit is the quantum coherence of the individual Qubit and therefore high quality Josephson junctions are required. Electron-beam lithography in combination with in-situ preparation of the Josephson junctions have successfully been fabricated and measured at low temperatures. 3. Development of superconducting nano-wires for quantum-phase slip dynamics: The quantum phase slip phenomena in superconducting nano-wire junctions is dual to the Cooper pair tunneling phenomena in Josephson junction. The nano-wires employed to observe the effect are required to be only a few ten nanometer wide and set therefore stringent limits to the fabrication tools. Utilizing the dedicated electron beam writer, wires which fulfill these requirements have been successfully fabricated and characterized at low temperatures.

Projektbezogene Publikationen (Auswahl)

 
 

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