Ab initio description of semiconductor nanocrystals

The special research program IR-ON develops new semiconductor nanostructures to explore new physical effects and to study new device concepts to solve a real world, macro-scale problem, namely the shortage of photonic devices for the infrared (2-20μm) wavelength range.

Our quality of life, safety, and environmental legacy are all directly affected by the chemical environment we live in and leave behind. Recent geopolitical events have created an increased demand for new public security systems. The optical absorption lines of many important chemical compounds (drugs, explosives and hazardous chemicals) fall into the infrared spectral region. Thus, infrared photonics is needed for environmental sensing, fast trace gas detection, control of hazardous material, pollution control, and, equally important, medical monitoring applications.

The realization of semiconductor nanostructures, in particular of quantum dots, offers fascinating perspectives for the development of new devices. Since semiconductor quantum dots resemble "artificial" atoms, their apparent "quantum" nature can be combined with advantages of the "classical" semiconductor world. Semiconductor "atoms" can be contacted with wires, integrated in circuits and built with high integration. The confinement to the
nanometer scale (<100nm <100·10-9 m) creates quantized energy levels with energy differences corresponding to the infrared spectral region. Nanostructuring of semiconductors adds new functionality - infrared optical activity. The goal of the joint effort IR-ON is to investigate, understand, and make use of this infrared optical activity which is entirely determined by quantum size effects. Quantum engineering allows the design of the optical properties to the applications´demand. One fascinating goal is to make Silicon optically active by employing Si/Ge nanostrucutres - eventually giving optical sensing capabilities to future high integrated circuits.

The possibility to contact and control individual, i.e. single quantum dots is a challenging long term goal of IR-ON. Single quantum dot detectors will show unsurpassed narrow absorptions lines for ultra precise spectroscopy and sensors. By implementing single electron control we will develop quantum dot detectors capable of detecting single photons or emitting single photons.

This research effort is carried out by leading Austrian semiconductor and nano technology research groups from the TU-Wien and the University Linz with strong support by computational materials scientists (University Vienna) and leading mesoscopic theorists from the TU-München.