A5087887061- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- solar cell performance optimization
- Ga2O3 and related materials
- Electron and X-Ray Spectroscopy Techniques
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
- Quantum Dots Synthesis And Properties
- Solar Thermal and Photovoltaic Systems
- Ion-surface interactions and analysis
- Thin-Film Transistor Technologies
- Chemical and Physical Properties of Materials
- Surface and Thin Film Phenomena
- Silicon and Solar Cell Technologies
- Advanced Chemical Physics Studies
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Photocatalysis Techniques
- Electrocatalysts for Energy Conversion
- Solar-Powered Water Purification Methods
- Transition Metal Oxide Nanomaterials
- Photovoltaic Systems and Sustainability
- TiO2 Photocatalysis and Solar Cells
- GaN-based semiconductor devices and materials
Technische Universität Ilmenau
2016-2025
Technical University of Darmstadt
2022
Kirchhoff (Germany)
2014-2016
Helmholtz-Zentrum Berlin für Materialien und Energie
2013
To date, III–V semiconductor-based tandem devices with GaInP top photoabsorbers show the highest solar-to-electricity or solar-to-fuel conversion efficiencies. In photoelectrochemical (PEC) cells, however, semiconductors are sensitive, in terms of photochemical stability and, therefore, require suitable functional layers for electronic and chemical passivation. GaN films discussed as promising options this purpose. The band alignment between such a protection layer semiconductor should be...
Using silicon in multijunction photocells leads to promising device structures for direct photoelectrochemical water splitting. In this regard, photoelectron spectra of surfaces are used investigate the energetic condition contact formation. It is shown that Fermi‐level position at surface differs from values expected their bulk doping concentrations, indicating significant band bending which may limit overall efficiency. study, influence different preparation procedures p‐ and n‐doped Si...
Abstract AlInP (001) is widely utilized as a window layer in optoelectronic devices, including world‐record III‐V multi‐junction solar cells and photoelectrochemical (PEC) cells. The chemical electronic properties of depend on its surface reconstruction, which impacts interaction with electrolytes PEC applications passivation layers. This study investigates reconstructions using density functional theory experimental methods. Phosphorus‐rich (P‐rich) indium‐rich (In‐rich) surfaces are...
Renewable ("green") hydrogen production through direct photoelectrochemical (PEC) water splitting is a potential key contributor to the sustainable energy mix of future. We investigate indium phosphide (InP) as reference material among III–V semiconductors for PEC and photovoltaic (PV) applications. The p(2 × 2)/c(4 2)-reconstructed phosphorus-terminated p-doped InP(100) (P-rich p-InP) surface focus our investigation. employ time-resolved two-photon photoemission (tr-2PPE) spectroscopy study...
Metalorganic vapor phase epitaxy of III-V compounds commonly involves arsenic. We study the formation atomically well-ordered, As-modified Si(100) surfaces and subsequent growth GaP/Si(100) quasisubstrates in situ with reflection anisotropy spectroscopy. Surface symmetry chemical composition are measured by low energy electron diffraction X-ray photoelectron spectroscopy, respectively. A two-step annealing procedure initially monohydride-terminated, (1 × 2) reconstructed As leads to a...
Stable InP (001) surfaces are characterized by fully occupied and empty surface states close to the bulk valence conduction band edges, respectively. The present photoemission data show, however, a Fermi level pinning only slightly below midgap energy which gives rise an appreciable bending. By means of density functional theory calculations, it is shown that this apparent discrepancy due defects form at finite temperature. In particular, desorption hydrogen from metalorganic vapor phase...
Artificial leaves could be the breakthrough technology to overcome limitations of storage and mobility through synthesis chemical fuels from sunlight, which will an essential component a sustainable future energy system. However, realization efficient solar‐driven artificial leaf structures requires integrated specialized materials such as semiconductor absorbers, catalysts, interfacial passivation, contact layers. To date, no competitive system has emerged due lack scientific understanding,...
In the pursuit of high-efficiency tandem devices for solar energy conversion based on III-V-semiconductors, low-defect III-V nucleation Si(100) substrates is essential. Here, hydrogen and arsenic are key ingredients in all growth processes with respect to industrially scalable metalorganic vapor phase epitaxy. Our study provides insight into surface preparation initial stage nucleation. The samples investigated, prepared different offcut angles, show single domain surfaces consisting rows...
Planar GaP epilayers on Si(111) are considered as virtual substrates for III–V-related optoelectronic devices such high-efficiency nanowire-based tandem absorber structures solar energy conversion, next generation LEDs, and fast photodetectors. Rotational twin domains in heteroepitaxial found to strongly impede vertical nanowire growth. We investigate the twin-induced defect density surface morphology of B-type GaP/Si(111) dependence nucleation process by metalorganic chemical vapor...
Nanowire growth on heteroepitaxial GaP/Si(111) by metalorganic vapor phase epitaxy requires the [-1-1-1] face, i.e., GaP(111) material with B-type polarity. Low-energy electron diffraction (LEED) allows us to identify polarity of GaP grown Si(111), since (2×2) and (1×1) surface reconstructions are associated GaP(111)A GaP(111)B, respectively. In dependence pre-growth treatment Si(111) substrates, we were able control buffers. films H-terminated exhibited A-type polarity, while Si surfaces...
Abstract The current efficiency records for generating green hydrogen via solar water splitting are held by indium phosphide (InP)‐based photo‐absorbers, protected TiO 2 layers grown through atomic layer deposition (ALD). InP is also a leading material photonic integrated circuits and computing, where ultrafast near‐surface behavior key. A previous study described electronic pathways at the phosphorus‐rich (P‐rich) surface of p‐doped InP(100) using time‐resolved two‐photon photoemission...
Multiabsorber structures for photoelectrochemical devices based on III–V semiconductor compounds enable direct solar-to-fuel conversion with the highest efficiencies to date as their tunable band gaps allow optimal exploitation of solar spectrum. In monolithic tandem record devices, GaInP is frequently utilized tune suitable gap energies use a top photoabsorber or charge-selective contact. Therefore, detailed understanding reactions at GaInP–electrolyte heterointerface particular interest...
Total energy and electronic structure calculations based on density functional theory are performed in order to determine the atomic properties of clean hydrogen‐adsorbed Al 0.5 In P(001) surfaces. It is found that most stable surfaces obey electron‐counting rule characterized by surface atom dimerization. The dimer‐related states predicted occur vicinity bulk band edges. For a very narrow range preparation conditions, ab initio thermodynamics predicts metal wires formed cations. A covered...
We report a detailed structure and defect characterization study on gallium phosphide (GaP) layers integrated silicon (Si) (001) via silicon-germanium (SiGe) buffer layers. The presented approach uses an almost fully relaxed SiGe heterostructure of only 400 nm thickness whose in-plane lattice constant is matched to GaP—not at room but GaP deposition temperature. Single crystalline, pseudomorphic 270 thick successfully grown by metalorganic chemical vapour Si0.85Ge0.15/Si(001) heterosystem,...