Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 46: Transport Properties (joint session HL/TT)
TT 46.8: Vortrag
Donnerstag, 20. März 2025, 17:00–17:15, H13
Quantum confinement and stoichiometry fluctuations in nm-thin SiGe layers — •Daniel Dick1,2,3,4, Florian Fuchs1,2,3, Sibylle Gemming2,4, and Jörg Schuster1,2,3 — 1Center for Micro- and Nanotechnology, TU Chemnitz, Germany — 2Center for Materials, Architecture and Integration of Nanomembranes, TU Chemnitz, Germany — 3Fraunhofer Institute for Electronic Nanosystems (ENAS), Chemnitz, Germany — 4Institute of Physics, TU Chemnitz, Germany
We simulate biaxially strained SiGe layers of varying thickness in the range of a few nanometers, as found in the base layer of heterojunction bipolar transistors (HBTs). At this length scale, local fluctuations in atomic concentrations can strongly influence the electronic properties of the device, especially the distribution of dopants like e.g. boron. Even at high doping concentrations, only a single atom is present at a 1 nm2 cross section of the layer on average.
Employing a new parameterization of silicon and germanium in the framework of extended Hückel theory (EHT), we calculate the local band gap for different permutations of the atomic structure. Various distributions of boron atoms are simulated. We study the impact of locally increased and decreased concentrations on the band gap. By varying layer thickness, we evaluate the effects of quantum confinement and how it impacts transport properties of the thin layer in contrast to bulk material.
Keywords: SiGe; alloy; quantum confinement; Electronic structure theory; Extended Hückel theory