A5025840578- Topological Materials and Phenomena
- Graphene research and applications
- Photonic and Optical Devices
- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
- Semiconductor Lasers and Optical Devices
- Advanced Condensed Matter Physics
- Quantum many-body systems
- Advanced Photonic Communication Systems
- Physics of Superconductivity and Magnetism
- Phase-change materials and chalcogenides
- Silicon Nanostructures and Photoluminescence
- GaN-based semiconductor devices and materials
- 2D Materials and Applications
- Advanced Semiconductor Detectors and Materials
- Silicon and Solar Cell Technologies
- Chalcogenide Semiconductor Thin Films
- Integrated Circuits and Semiconductor Failure Analysis
- Surface and Thin Film Phenomena
- Thin-Film Transistor Technologies
Forschungszentrum Jülich
2016-2025
Jülich Aachen Research Alliance
2015-2024
RWTH Aachen University
2019-2024
Grunberger Diabetes Institute
2018
Stadtwerke Jülich (Germany)
2018
Ernst Ruska Centre
2015
Shanghai Institute of Microsystem and Information Technology
2013
University of Chinese Academy of Sciences
2013
Paul Scherrer Institute
2006-2008
Paul Drude Institute for Solid State Electronics
2003-2005
The strong correlation between advancing the performance of Si microelectronics and their demand low power consumption requires new ways data communication. Photonic circuits on are already highly developed except for an eligible on-chip laser source integrated monolithically. recent demonstration optically pumped waveguide made from Si-congruent GeSn alloy, monolithical integration has taken a big step forward way to all-inclusive nanophotonic platform in CMOS. We present group IV microdisk...
Abstract Three-dimensional topological insulators are fascinating materials with insulating bulk yet metallic surfaces that host highly mobile charge carriers locked spin and momentum. Remarkably, surface currents tunable direction magnitude can be launched tailored light beams. To better understand the underlying mechanisms, current dynamics need to resolved on timescale of elementary scattering events (∼10 fs). Here, we excite measure photocurrents in model insulator Bi 2 Se 3 a time...
In this letter, we propose a heterostructure design for tunnel field effect transistors with two low direct bandgap group IV compounds, GeSn and highly tensely strained Ge in combination ternary SiGeSn alloy. Electronic band calculations show that Ge, used as channel, grown on Ge1−xSnx (x > 9%) buffer, source, becomes which significantly increases the tunneling probability. The ternaries are well suitable drain since they offer large indirect bandgap. growth of such heterostructures...
The recent observation of a fundamental direct bandgap for GeSn group IV alloys and the demonstration low temperature lasing provide new perspectives on fabrication Si photonic circuits. This work addresses progress in alloy epitaxy aiming at room lasing. Chemical vapor deposition with high Γ- to L-valley energy separation large thicknesses efficient optical mode confinement is presented discussed. Up 1 μm thick layers Sn contents up 14 at. % were grown relaxed Ge buffers, using Ge2H6 SnCl4...
We report on the observation of photogalvanic effects in epitaxially grown Sb2Te3 and Bi2Te3 three-dimensional (3D) topological insulators (TI). show that asymmetric scattering Dirac fermions driven back forth by terahertz electric field results a dc current. Because "symmetry filtration" current is generated surface electrons only provides an optoelectronic access to probe electron transport TI, domains orientation, details 3D TI even at room temperature.
3D topological insulators are a new state of quantum matter which exhibits both bulk band structure with an insulating energy gap as well metallic spin-polarized Dirac fermion states when interfaced topologically trivial material. There have been various attempts to tune the point desired energetic position for exploring its unusual properties. Here we show direct experimental proof by angle-resolved photoemission realization vertical p-n junction made heterostructure two different binary TI...
A comprehensive study of optical transitions in direct-bandgap Ge0.875Sn0.125 group IV alloys via photoluminescence measurements as a function temperature, compressive strain and excitation power is performed. The analysis the integrated emission intensities reveals strain-dependent indirect-to-direct bandgap transition, good agreement with band structure calculations based on 8-band k·p deformation potential methods. We have observed quantified Γ valley–heavy hole valley–light at low...
GeSn on Si light-emitting diodes (LEDs) is investigated for different Sn concentrations up to 4.2% and they are compared with an LED made from pure Ge Si. The LEDs realized in-situ doped pin junctions in virtual substrates. device structures grown a special ultra-low temperature molecular beam epitaxy process. All clearly show direct bandgap electroluminescence emission at room temperature. light intensity of the compressively strained increases higher concentration. in-plane strain...
A combined theoretical and experimental study reveals evidence for the dual topological insulating character of stoichiometric natural superlattice phase $\mathrm{Bi_{1}Te_{1}}=\mathrm{[Bi_{2}]_{1}[Bi_{2}Te_{3}]_{2}}$, being a stack alternating Bi bilayers two quintuple layers $\mathrm{Bi_{2}Te_{3}}$. We identify $\mathrm{Bi_{1}Te_{1}}$ by density functional theory to exhibit non trivial time-reversal symmetry-driven $\mathbb{Z}_{2}=(0;001)$ additionally mirror-symmetry induced mirror Chern...
We report on the observation of a terahertz radiation induced photon drag effect in epitaxially grown $n$- and $p$-type (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ three dimensional topological insulators with different antimony concentrations $x$ varying from 0 to 1. demonstrate that excitation polarized results $dc$ electric photocurrent. While at normal incidence current arises due photogalvanic surface states, oblique it is outweighed by trigonal effect. The developed microscopic model theory...
We present results on CVD growth and electro-optical characterization of Ge(0.92)Sn(0.08)/Ge p-i-n heterostructure diodes. The suitability Ge as barriers for direct bandgap GeSn active layers in different LED geometries, such double heterostructures multi quantum wells is discussed based electroluminescence data. Theoretical calculations by effective mass 6 band k∙p method reveal low barrier heights this specific structure. Best configurations offer only a maximum height electrons about 40...
We investigated Raman vibrational modes in silicon-germanium-tin layers grown epitaxially on germanium/silicon virtual substrates using reduced pressure chemical vapor deposition. Several excitation wavelengths were utilized to accurately analyze shifts ternary with uniform silicon and tin content 4–19 2–12 at. % ranges, respectively. The a 633 nm laser was found be optimal leading clear detection an unambiguous identification of all first order the alloy. influence both strain composition...
The epitaxial growth of Ge and GeSn alloys on Si(100) by Reduced Pressure Chemical Vapor Deposition is discussed. Particular emphasis placed the kinetics in temperature window between 375°C 475°C. Using Ge2H6 precursor H2 carrier gas a low activation energy 0.7 eV was found for which further decreases to 0.5 N2 gas. Thin layers with high crystalline quality are aimed may be used as buffers layers. Furthermore, up 10 at.% Sn synthesized at temperatures employing SnCl4 precursors. All exhibit...
The structural perfection of the topological insulator (TI) Bi2Te3 is a key issue for its employment in future device applications. State art TIs, featuring exotic electronic properties, predominantly suffer from defects such as twin domains. A suppression domains molecular beam epitaxy-grown thin films on Si(111) substrates—measured by X-ray diffraction pole figure scans—is presented this paper. numerical analysis van der Waals potentials was performed, revealing nucleation collinear with...
The integration of semiconductor Josephson junctions (JJs) in superconducting quantum circuits provides a versatile platform for hybrid qubits and offers powerful way to probe exotic quasiparticle excitations. Recent proposals using circuit electrodynamics (cQED) detect topological superconductivity motivate the novel materials such circuits. Here, we report on realization transmon implemented with (Bi0.06Sb0.94)2Te3 insulator (TI) JJs ultrahigh vacuum fabrication techniques. Microwave...
This letter presents the epitaxial growth and characterization of a heterostructure for an electrically injected laser, based on strained GeSn active well. The elastic strain within well can be tuned from compressive to tensile by high quality large Sn content (Si)GeSn buffers. optimum combination alloying softens requirements upon indirect direct bandgap transition. We theoretically discuss strain-doping relation maximum net gain in layer. Employing 0.5% enables reasonable optical values...
Layered materials such as graphene, bi-, and multilayer graphene well various compounds of topological insulators are currently in the focus interest due to their extraordinary physical properties related Dirac surface states. The ability grow thin films these complex layered is key explore fundamental phenomena giving insights into modern solid-state physics. However, composed layers only weakly bonded via van der Waals forces offer unmatched challenges for deposition epitaxial films. Here,...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation L. Plucinski, G. Mussler, J. Krumrain, A. Herdt, S. Suga, D. Grützmacher, C. M. Schneider; Robust surface electronic properties of topological insulators: Bi2Te3 films grown by molecular beam epitaxy. Appl. Phys. Lett. 30 May 2011; 98 (22): 222503. https://doi.org/10.1063/1.3595309 Download citation file: Ris...
Three-dimensional topological insulators (TIs) have attracted tremendous interest for their possibility to host massless Dirac Fermions in topologically protected surface states (TSSs), which may enable new kinds of high-speed electronics. However, recent reports outlined the importance band bending effects within these materials, results an additional two-dimensional electron gas (2DEG) with finite mass at surface. TI surfaces are also known be highly inhomogeneous on nanoscale, is masked...
Ternary (Bi1-xSbx)2Te3 films with an Sb content between 0 and 100% were deposited on a Si(111) substrate by means of molecular beam epitaxy. X-ray diffraction measurements confirm single crystal growth in all cases. The is determined photoelectron spectroscopy. Consistent values the are obtained from Raman Scanning spectroscopy reveals that layers intermediate show spatial composition inhomogeneities. observed spectra broadening angular-resolved photoemission (ARPES) also attributed to this...
We synthesized and spectroscopically investigated monolayer (ML) C60 on the topological insulator (TI) Bi4Te3. This C60/Bi4Te3 heterostructure is characterized by an excellent translational order in a novel (4 × 4) superstructure (9 9) cell of Angle-resolved photoemission spectroscopy (ARPES) reveals that ML accepts electrons from TI at room temperature, but no charge transfer occurs low temperatures. temperature-dependent doping further Raman spectroscopy, photoluminescence (PL),...