A5043757011- Electrical and Thermal Properties of Materials
- Microwave Engineering and Waveguides
- 3D IC and TSV technologies
- Semiconductor Lasers and Optical Devices
- Microwave Dielectric Ceramics Synthesis
- Ferroelectric and Piezoelectric Materials
- Silicon and Solar Cell Technologies
- Electronic Packaging and Soldering Technologies
- GaN-based semiconductor devices and materials
- Advanced Sensor Technologies Research
- Advanced MEMS and NEMS Technologies
- Semiconductor Quantum Structures and Devices
- Advanced Antenna and Metasurface Technologies
- Acoustic Wave Resonator Technologies
- Advanced machining processes and optimization
- Thin-Film Transistor Technologies
- Advanced Measurement and Metrology Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Photonic and Optical Devices
- Antenna Design and Analysis
- Semiconductor materials and devices
- Gas Sensing Nanomaterials and Sensors
- Iterative Learning Control Systems
- Radio Frequency Integrated Circuit Design
- Semiconductor materials and interfaces
Technische Universität Ilmenau
2016-2025
TU Dresden
2013-2024
University of Groningen
2024
Heidelberg University
2024
Kirchhoff (Germany)
2007-2023
Fraunhofer Institute of Optronics, System Technologies and Image Exploitation
2021-2023
Ruhr University Bochum
1998-2023
Karlsruhe Institute of Technology
2023
University of Bremen
2023
Joint Research Center
2022
We pushed direct green laser diodes towards longer wavelengths at 524–532 nm based on improvements of epitaxial design and material quality c-plane GaN substrate. Mounted ridge show significant performance improvement in cw operation. For 524 laser, wall plug efficiency up to 2.3% 50 mW optical output power is achieved. In pulse mode operation we demonstrate broad-area test lasers with an emission wavelength 531.7 nm. Nonpolar polar substrates are compared respect indium content InGaN...
Generative Adversarial Networks (GANs) produce high-quality images but are challenging to train. They need careful regularization, vast amounts of compute, and expensive hyper-parameter sweeps. We make significant headway on these issues by projecting generated real samples into a fixed, pretrained feature space. Motivated the finding that discriminator cannot fully exploit features from deeper layers model, we propose more effective strategy mixes across channels resolutions. Our Projected...
We demonstrate direct green laser operation from InGaN based diodes at wavelengths as long 515.9 nm with 50 mW output power in pulse operation. A factor of ∼10 defect reduction for the In-rich quantum wells on improvements epitaxial growth process and design active layers c-plane GaN-substrates makes it possible to room temperature. Micrometer-scale photoluminescence mappings electro-optical measurements confirm nonradiative defects emitting layers. The 11 μm broad-area gain-guided...
During the past years, much research work has been focused on efficiently harvesting solar energy with black silicon (b-Si). However, semiconductor Si can only utilize wavelength smaller than λ = 1110 nm (bandgap Eg 1.12 eV) for photovoltaic applications or photoelectrochemical conversions. Light beyond band edge (above nm) cannot be used. Here, we prepared highly conductive b-Si without an apparent optical bandgap by a reactive ion etching process, which largely absorb light wide range and...
The use of open-source software is crucial for the digitalization manufacturing, including implementation Digital Twins as envisioned in Industry 4.0. This research paper provides a comprehensive comparison free and implementations reactive Asset Administration Shell (AAS) creating Twins. A structured search on GitHub Google Scholar was conducted, leading to selection four detailed analysis. Objective evaluation criteria were defined, testing framework created test support most common AAS...
The purpose of this paper is a detailed comparison selected luminescence and lock-in thermography (LIT) results on one exemplary sample the drawing corresponding conclusions. Our focus solar cells, but some investigations wafers will be discussed as well. help to decide which characterization tools are needed solve technological problems. It demonstrated that imaging may widely replace LIT with respect analysis recombination-active bulk defects, cracks, series resistance, junction breakdown...
The concept of digital twins (DT) has already been discussed some decades ago. Digital representations physical assets are key components in industrial applications as they the basis for decision making. What is new conceptual approach to consider DT well-defined software entities themselves that follow whole lifecycle their counterparts from engineering, operation up discharge, and hence, have own type description, identity, lifecycle. This paper elaborates on this idea argues need...
Reactive bonding can overcome the issues associated with conventional soldering processes, such as potential damage to heat-sensitive components and creation of thermomechanical stress due differing coefficients thermal expansion. The risk be reduced by using localized heat sources like reactive multilayer systems (RMS), which is already a well-established option in field silicon or metal bonding. Adapting this process other materials, low temperature co-fired ceramics (LTCC), difficult...
In this study, we present an adaptive anisotropic finite element method (FEM) and demonstrate how computational efficiency can be increased when applying the to simulation of blood flow in cardiovascular system. We use SUPG formulation for transient 3D incompressible Navier–Stokes equations which are discretised by linear elements both pressure velocity field. Given pulsatile nature vessels have pursued adaptivity based on average over a cardiac cycle. Error indicators derived define mesh...
Abstract In this paper we investigate the waveguiding (WG) of direct green InGaN laser diodes grown on c ‐plane GaN substrates. The problem parasitic modes emerges due to reduced refractive index difference between waveguide and AlGaN cladding layers for compared blue emitting diodes. We discuss several approaches avoid substrate modes. different materials designs optimized WG using a 1D transfer matrix simulation tool.
Abstract The challenges of green InGaN lasers are discussed concerning material quality as a function composition, quantum well design and piezoelectrical fields. Investigations polar designs comparison with simulated non‐polar structures demonstrate that the indium rich layers is more important than influence interface charges. A high risk dark spots at In concentrations 26–33% observed. Small changes about 2% significant reduce or increase quantity size luminescence areas. Polar trade‐off...
Abstract We present true green InGaN ridge waveguide (RWG) laser diodes (LDs) at 520 nm on c‐plane GaN substrates in pulse operation room temperature. Defect reduction the In‐rich quantum wells by improving growth conditions of epitaxial layers is key parameter to demonstrate this wavelength. Carrier lifetime measurements combination with electroluminescence (EL) data and simulations competing recombination processes below threshold confirm that defects light emitting essential realize...
We study recombination properties and the formation of base contacts, which are realized by local laser ablation a dielectric stack subsequent full-area screen printing an Al paste. Based on charge-carrier lifetime measurements using camera-based calibration-free dynamic infrared mapping technique, we determine contact reverse saturation current densities as low <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex...
In this paper, we investigate the surface recombination of local screen-printed aluminum contacts applied to rear passivated solar cells. We measure velocity by microwave-detected photoconductance decay measurements on test wafers with various contact geometries and compare two different pastes. The paste which is optimized for shows a deep uniform back field that results in Smet = 600 cm/s 1.5 Ωcm p-type silicon. contrast, standard Al full-area metallization non-uniform 2000 same material....
In this paper, we investigate the impact of rear surface passivation, silicon base material and local aluminum contacts applied to side passivated solar cells with a homogenously doped emitter at front. We compare different dielectric passivation layers (SiO2, Al2O3, SiNx) on high-efficiency level using 125×125 mm2 156×156 p-type Cz wafers. It turns out that applying an Al2O3/SiNx layer stack outperforms all other due its excellent as well optical properties. determine light induced...
Mobile laser projection is of great commercial interest. Today, a key parameter in embedded mobile applications the optical output power and wall plug efficiency blue green lasers. We report on improvements performance true riedge waveguide InGaN lasers at 452nm with cw-output up to 800mW overstress mono mode operation 500mW temperatures range 20°C 80°C. succeeded high almost temperature independent efficiencies >20% stable levels from 200 cw-operation. Due several our diodes we now estimate...
In photovoltaic (PV) modules, the interconnection of solar cells is critical in terms mechanical stability and resistive power losses. this study, we analyze large-area 15.6 × cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> industrial p-type passivated emitter rear cell (PERC) For our analysis, prepare a 3 minimodule from PERC with soldering pads efficiencies up to 20.0%. We measure significant cell-to-module (CTM) loss 8% at module....
Experimental gain spectra of 450 and 490 nm laser diodes on c-plane GaN are analyzed by detailed comparison with the results a fully microscopic theory. The calculation shows importance electron LO-phonon coupling. whole spectral shape, not only low energy tail, is strongly influenced contribution. inhomogeneous broadening parameter increases factor about two for cyan diode in blue structure. This indicates an increase alloy thickness fluctuations longer wavelength material.
Polarimetric radio wave processing becomes of increasing interest for very high-data rate wireless transmission and short-range radar at millimeter-waves (mm-W). This goes along with the huge bandwidth 7 to 9 GHz, which is available worldwide in 60 GHz unlicensed band. In this paper, we propose a ultra-wideband (UWB) polarimetric multiple-input-multiple-output (MIMO) sensing system architecture signal communications radar. Demonstration measurements were made by using an UWB interface. By...