A5024641733- Nanowire Synthesis and Applications
- Semiconductor Quantum Structures and Devices
- Advancements in Semiconductor Devices and Circuit Design
- Quantum Dots Synthesis And Properties
- ZnO doping and properties
- Semiconductor Lasers and Optical Devices
- Advanced Semiconductor Detectors and Materials
- Photonic and Optical Devices
- Photonic Crystals and Applications
- Semiconductor materials and devices
- Semiconductor materials and interfaces
- GaN-based semiconductor devices and materials
- Organic Electronics and Photovoltaics
- Experimental Learning in Engineering
- Organic Light-Emitting Diodes Research
- Ga2O3 and related materials
- Anodic Oxide Films and Nanostructures
- Ion-surface interactions and analysis
- Cloud Computing and Remote Desktop Technologies
- Electronic and Structural Properties of Oxides
- Advanced Materials Characterization Techniques
- Silicon and Solar Cell Technologies
- Silicon Nanostructures and Photoluminescence
- Advanced Electron Microscopy Techniques and Applications
- Biomedical and Engineering Education
Forschungsverbund Berlin
2019-2024
Paul Drude Institute for Solid State Electronics
2017-2024
National University of Distance Education
2017
Consejo Superior de Investigaciones Científicas
2011-2015
Centro Nacional de Microelectrónica
2009-2014
Australian National University
2006
We present a fabrication method to produce site-controlled and regularly spaced InAs/GaAs quantum dots for applications in optical information devices. The high selectivity of our epitaxial regrowth procedure can be used allocate the only positions predefined by ex-situ local oxidation atomic force nanolithography. obtained following this process quality which we have evaluated microphotoluminescence photon correlation experiments.
In this work, we present a fabrication process that combines atomic force microscopy (AFM) local oxidation nanolithography and molecular beam epitaxy (MBE) growth techniques in order to control both the nucleation site number of InAs quantum dots (QDs) inside different motifs printed on GaAs(001) substrates. We find presence B-type slopes (As terminated) pattern is main parameter for controlling selectivity growth. demonstrate either single QDs or multiple lateral arrangement (LQDAs) can be...
Surface energies play a dominant role in the self-assembly of three dimensional (3D) nanostructures. In this letter, we show that using surfactants to modify surface can provide means externally control nanostructure self-assembly, enabling synthesis novel hierarchical We explore Bi as surfactant growth InAs on {1-10} sidewall facets GaAs nanowires. The presence induces formation 3D islands by process resembling Stranski-Krastanov mechanism, which does not occur absence these surfaces....
In strained heteroepitaxy, two-dimensional layers can exhibit a critical thickness at which three-dimensional islands self-assemble, relieving misfit strain the cost of an increased surface area. Here we show that such morphological phase transition be induced on demand using surfactants. We explore Bi as surfactant in growth InAs GaAs(110), and find presence induces Stranski-Krastanov 3D islands, while without always favors 2D layer formation. Exposing static two monolayer thick to rapidly...
Core-shell GaAs-based nanowires monolithically integrated on Si constitute a promising class of nanostructures that could enable light emitters for fast inter- and intrachip optical connections. We introduce fabricate novel coaxial GaAs/(In,Ga)As dot-in-a-well nanowire heterostructure to reach spontaneous emission in the transparent region, which is crucial applications photonics. Specifically, we achieve room temperature at 1.27 $\mu$m telecommunication O band. The presence quantum dots...
While the properties of wurtzite GaAs have been extensively studied during past decade, little is known about influence crystal polytype on ternary (In,Ga)As quantum well structures. We address this question with a unique combination correlated, spatially resolved measurement techniques core–shell nanowires that contain extended segments both zincblende and polytypes. Cathodoluminescence hyperspectral imaging reveals blue-shift emission energy by 75 ± 15 meV in segment. Nanoprobe X-ray...
We present growth and optical characterization measurements of single InAs site-controlled quantum dots (SCQDs) grown by molecular beam epitaxy on GaAs (001) patterned substrates atomic force microscopy oxidation lithography. SCQDs directly the surface were used as a seed layer strain template for nucleation optically active SCQDs. The preservation initial geometry engraved pattern motifs after re-growth interface preparation process, lack buffer prior to deposition development suitable...
This work studies the selective nucleation of InAs within nanoholes on GaAs(001) substrates patterned by atomic force microscopy local oxidation. The effects substrate temperature and As4 overpressure during deposition directly (without a GaAs buffer layer) are considered. It is found that when deposited at 510 °C under low overpressure, single quantum dot per nanohole obtained for broad range sizes pattern motifs. use these dots as seed nuclei vertical stacking optically active...
We investigate L7 photonic crystal microcavities (PCMs) fabricated by epitaxial re-growth of GaAs pre-patterned substrates, containing InAs quantum dots. The resulting PCMs show hexagonal shaped nano-holes due to the development preferential crystallographic facets during step. Through a careful control fabrication processes, we demonstrate that modes are preserved throughout process. quality factor (Q) in re-grown strongly depends on relative orientation between lattice and directions....
We have studied the optical properties of InAs site-controlled quantum dots (SCQDs) grown on pre-patterned GaAs substrates. Since nucleates preferentially lithography motifs, location resulting QDs is determined by pattern, which fabricated local oxidation nanolithography. Optical characterization has been performed such SCQDs to study fundamental and excited states. At ground state different exciton complex transitions about 500 μeV linewidth identified fine structure splitting neutral (≈65...
Nanoprobe X-ray diffraction (nXRD) using focused synchrotron radiation is a powerful technique to study the structural properties of individual semiconductor nanowires. However, when performing experiment under ambient conditions, required high dose and prolonged exposure times can lead damage. To unveil origin damage, comparison made nXRD experiments carried out on nanowires in their as-grown geometry both conditions He atmosphere at microfocus station P08 beamline third-generation source...
Misfit strain in core-shell nanowires can be elastically released by nanowire bending case of asymmetric shell growth around the core. In this work, we investigate GaAs during overgrowth an InxGa1-xAs caused avoiding substrate rotation. We observe that direction depends on nature substrate's oxide layer, demonstrated Si substrates covered native and thermal layers. Further, follow evolution time-resolvedin situx-ray diffraction measurements deposition shell. The XRD give insight into...
Spin-coating of poly(ethylenimine) (PEI) has been used to reduce the work function GaAs (001), (110), (111)A and (111)B.
Here we report on the non-uniform shell growth of In x Ga 1− As GaAs nanowire (NW) core by molecular beam epitaxy (MBE).
Abstract (In, Ga) alloy droplets are used to catalyse the growth of Ga)As nanowires by molecular beam epitaxy on Si(111) substrates. The composition, morphology and optical properties these can be tuned employed elemental fluxes. To incorporate more than 10% In, a high In/(In+Ga) flux ratio above 0.7 is required. We report maximum In content almost 30% in bulk for an 0.8. However, with increasing ratio, nanowire length diameter notably reduced. Using photoluminescence cathodoluminescence...
In this work we show two different procedures of fabrication aiming towards the systematic positioning single InAs quantum dots (QDs) coupled to a GaAs photonic crystal (PC) microcavity. The approaches are based on molecular beam epitaxial (MBE) growth site-controlled QDs (SCQDs) pre-patterned structures. PC microcavity (PCM) is introduced previous or after growth, each case. We demonstrate SCQD nucleation PCMs and method perform QD respect an etched ruler that used position structure...
We explore the Bi-surfactant-directed self-assembly and structure of InAs quantum dots (QDs) grown on GaAs(110) by molecular beam epitaxy. The addition a Bi flux during deposition changes growth mode from two-dimensional (2D) Frank–van der Merwe to Stranski–Krastanov (SK), resulting in formation three-dimensional (3D) islands surface. Furthermore, exposing static 2D layers induces rearrangement strained layer into 3D islands. effect varying thickness for these two approaches, observing...
The development of integrated vertical III-V nanowire (NW) stimulated emitters in silicon photonics while achieving an efficient light coupling through NW lasers into horizontal optical waveguides is demanding. This mainly due to the directionality and contradiction simultaneously satisfied low threshold emission conditions NWs from waveguide. However, we propose a new, best our knowledge, design by taking advantage resonating features ring structures theoretically demonstrate that...
The impact of electrical current on the structure single free‐standing Be‐doped GaAs nanowires grown a Si 111 substrate is investigated. Single have been structurally analyzed by X‐ray nanodiffraction using synchrotron radiation before and after application an current. conductivity measurements in their as‐grown geometry realized via W‐probes installed inside dual‐beam focused ion beam/scanning electron microscopy chamber. Comparing reciprocal space maps Bragg reflection, extracted...
(In,Ga) alloy droplets are used to catalyse the growth of (In,Ga)As nanowires by molecular beam epitaxy on Si(111) substrates. The composition, morphology and optical properties these can be tuned employed elemental fluxes. To incorporate more than 10% In, a high In/(In+Ga) flux ratio above 0.7 is required. We report maximum In content almost 30% in bulk for an 0.8. However, with increasing fl ux ratio, nanowire length diameter notably reduced. Using photoluminescence cathodoluminescence...