Johannes Kepler University of Linz

About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Thin film & Quantum dot. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

Energetic and Entropic Contributions to Self-Assembly of Binary Nanocrystal Superlattices: Temperature as the Structure-Directing Factor

Abstract: We studied the effect of temperature on self-assembly of monodisperse colloidal nanocrystals into single-component and binary superlattices. Temperature, which serves as a weighting factor for the internal energy (U) and entropy (S) contributions to the Helmholtz free energy F = U − TS, allows tailoring relative weights of the interparticle interactions and free-volume entropy during the formation of nanocrystal superlattices. Temperature also provides a convenient tool for directing self-assembly of nanocrystals toward desired superlattice structures. We found that temperature strongly affects the structures of binary superlattices self-assembled from the mixtures of CdSe + PbS nanocrystals and PbSe + Pd nanocrystals. In the former case, small Hamaker constants for CdSe and PbS nanocrystals led to a relatively simple phase diagram, including only high-density NaZn13-, AlB2-, and NaCl-type binary superlattices. In contrast, binary superlattices self-assembled at different temperatures from PbSe and Pd nan...

Collective symbolic coping with new technology: knowledge, images and public discourse

Abstract: Using data from policy analyses, media analyses and a European-wide survey about public perceptions of biotechnology conducted in 1996 and again in 1999, it is shown how a country's public develops an everyday understanding of a new technology (genetic modification) construed as potentially harmful by the media. To understand the reliance on images and related beliefs, we propose a theory of collective symbolic coping. It identifies four steps: first, the creation of awareness; second, production of divergent images; third, convergence upon a couple of dominant images in the public sphere; fourth, normalization. It is suggested that symbolic coping occurs in countries where a recent increase in policy activity and of media reporting has alerted the public; that this public show a high proportion of beliefs in menacing images; that these beliefs are relatively independent of pre-existing popular science knowledge; and that they are functionally equivalent to scientific knowledge in providing judgmental confidence and reducing self-ascribed ignorance. These propositions are shown to be true in Austria and Greece. Several implications of the theory are discussed, including social representation theory and public understanding of science.

Progress in plastic electronics devices

Abstract: ▪ Abstract Organic field-effect transistors (OFETs) based on solution-processible polymeric as well as small molecular semiconductors have shown impressive improvements in their performance during recent years. These devices have been developed to realize low-cost, large-area electronic products. This review gives an overview of the materials’ aspect, charge-transport, and device physics of OFETs, focusing mainly on the organic semiconductor and organic dielectric materials and their mutual interface. Recent developments in the understanding of the relationship between microstructure and charge transport, the influence of processing techniques, and gate dielectric are reviewed. Comparative data of charge-carrier mobility of most organic semiconductors have been compiled. Ambipolar charge transport in OFETs and its applications to integrated circuits as well as ambipolar light-emitting transistors are also reviewed. Many interesting questions regarding how the molecular and electronic structures at the int...

A germanium hole spin qubit.

Abstract: Holes confined in quantum dots have gained considerable interest in the past few years due to their potential as spin qubits. Here we demonstrate two-axis control of a spin 3/2 qubit in natural Ge. The qubit is formed in a hut wire double quantum dot device. The Pauli spin blockade principle allowed us to demonstrate electric dipole spin resonance by applying a radio frequency electric field to one of the electrodes defining the double quantum dot. Coherent hole spin oscillations with Rabi frequencies reaching 140 MHz are demonstrated and dephasing times of 130 ns are measured. The reported results emphasize the potential of Ge as a platform for fast and electrically tunable hole spin qubit devices.