Dr. rer. nat. Fariba Hatami
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Stand: 26.4.2026, 19:48:44 (Top-K=20, Min-Cosine=0.4)
- 104 Treffer60.3%
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- Interfaces in opto-electronic thin film multilayer devices
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- 1 Treffer56.4%
- Zuwendung im Rahmen des Programms „exist – Existenzgründungen aus der Wissenschaft“ aus dem Bundeshaushalt, Einzelplan 09, Kapitel 02, Titel 68607, Haushaltsjahr 2026, sowie aus Mitteln des Europäischen Strukturfonds (hier Euro-päischer Sozialfonds Plus – ESF Plus) Förderperiode 2021-2027 – Kofinanzierung für das Vorhaben: „exist Women“T56.4%
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- 74 Treffer55.7%
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- Lösung gekoppelter Probleme in der Nanoelektronik (nanoCOPS)
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Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
Nature · 887 Zitationen · DOI
Nano Letters · 355 Zitationen · DOI
We describe and experimentally demonstrate a technique for deterministic, large coupling between a photonic crystal (PC) nanocavity and single photon emitters. The technique is based on in situ scanning of a PC cavity over a sample and allows the precise positioning of the cavity over a desired emitter with nanoscale resolution. The power of the technique is demonstrated by coupling the PC nanocavity to a single nitrogen vacancy (NV) center in diamond, an emitter system that provides optically accessible electron and nuclear spin qubits.
Applied Physics Letters · 324 Zitationen · DOI
Strained GaSb quantum dots having a staggered band lineup (type II) are formed in a GaAs matrix using molecular beam epitaxy. The dots are growing in a self-organized way on a GaAs(100) surface upon deposition of 1.2 nm GaSb followed by a GaAs cap layer. Plan-view transmission electron microscopy studies reveal well developed rectangular-shaped GaSb islands with a lateral extension of ∼20 nm. Intense photoluminescence (PL) is observed at an energy lower than the GaSb wetting layer luminescence. This line is attributed to radiative recombination of 0D holes located in the GaSb dots and electrons located in the surrounding regions. The GaSb quantum dot PL dominates the spectrum up to high excitation densities and up to room temperature.
Strong Enhancement of Light–Matter Interaction in Graphene Coupled to a Photonic Crystal Nanocavity
2012Nano Letters · 308 Zitationen · DOI
We demonstrate a large enhancement in the interaction of light with graphene through coupling with localized modes in a photonic crystal nanocavity. Spectroscopic studies show that a single atomic layer of graphene reduces the cavity reflection by more than a factor of one hundred, while also sharply reducing the cavity quality factor. The strong interaction allows for cavity-enhanced Raman spectroscopy on subwavelength regions of a graphene sample. A coupled-mode theory model matches experimental observations and indicates significantly increased light absorption in the graphene layer. The coupled graphene–cavity system also enables precise measurements of graphene’s complex refractive index.
Physical review. B, Condensed matter · 244 Zitationen · DOI
The optical properties and dynamics of charge carriers in self-organized arrays of type-II (staggered band lineup) GaSb/GaAs quantum dots are studied. Interband absorption from type-II quantum dots is evidenced; the energetic positions of quantum dot absorption peaks coincide with those apparent in photoluminescence spectra. (Sb,As) intermixing with an antimony diffusion length of about 1 nm is found to make an important contribution to the observed transition energies. Dipole layer formation and quantum dot state filling contribute to the luminescence blueshift with increasing excitation density. The recombination rate of electrons with localized holes drastically depends on the average carrier density. When several carriers are localized at each dot, decay time constants around 5 ns, quite similar to type-I systems, are observed. Individual, spatially indirect excitons decay with much larger time constants close to 1 \ensuremath{\mu}s. The decay time of quantum dot luminescence is independent of the temperature in the measured range $T<~65\mathrm{K}$ as expected for zero-dimensional excitons.
Applied Physics Letters · 223 Zitationen · DOI
We report on controlling the spontaneous emission (SE) rate of a molybdenum disulfide (MoS<sub>2</sub>) monolayer coupled with a planar photonic crystal (PPC) nanocavity. Spatially resolved photoluminescence (PL) mapping shows strong variations of emission when the MoS<sub>2</sub> monolayer is on the PPC cavity, on the PPC lattice, on the air gap, and on the unpatterned gallium phosphide substrate. Polarization dependences of the cavity-coupled MoS<sub>2</sub> emission show a more than 5 times stronger extracted PL intensity than the un-coupled emission, which indicates an underlying cavity mode Purcell enhancement of the MoS<sub>2</sub> SE rate exceeding a factor of 70.
Optics Express · 179 Zitationen · DOI
We demonstrate second harmonic generation in photonic crystal nanocavities fabricated in the semiconductor gallium phosphide. We observe second harmonic radiation at 750 nm with input powers of only nanowatts coupled to the cavity and conversion effciency P(out)/P(2)(in,coupled)=430%/W. The large electronic band gap of GaP minimizes absorption loss, allowing effcient conversion. Our results are promising for integrated, low-power light sources and on-chip reduction of input power in other nonlinear processes.
Nano Letters · 154 Zitationen · DOI
Developing a nanoscale, integrable, and electrically pumped single mode light source is an essential step toward on-chip optical information technologies and sensors. Here, we demonstrate nanocavity enhanced electroluminescence in van der Waals heterostructures (vdWhs) at room temperature. The vertically assembled light-emitting device uses graphene/boron nitride as top and bottom tunneling contacts and monolayer WSe<sub>2</sub> as an active light emitter. By integrating a photonic crystal cavity on top of the vdWh, we observe the electroluminescence is locally enhanced (>4 times) by the nanocavity. The emission at the cavity resonance is single mode and highly linearly polarized (84%) along the cavity mode. By applying voltage pulses, we demonstrate direct modulation of this single mode electroluminescence at a speed of ∼1 MHz, which is faster than most of the planar optoelectronics based on transition metal chalcogenides (TMDCs). Our work shows that cavity integrated vdWhs present a promising nanoscale optoelectronic platform.
Applied Physics Letters · 153 Zitationen · DOI
We present biomedical imaging using a single frequency terahertz imaging system based on a low threshold quantum cascade laser emitting at 3.7THz (λ=81μm). With a peak output power of 4mW, coherent terahertz radiation and detection provide a relatively large dynamic range and high spatial resolution. We study image contrast based on water/fat content ratios in different tissues. Terahertz transmission imaging demonstrates a distinct anatomy in a rat brain slice. We also demonstrate malignant tissue contrast in an image of a mouse liver with developed tumors, indicating potential use of terahertz imaging for probing cancerous tissues.
Applied Physics Letters · 100 Zitationen · DOI
We demonstrate a compact spectrometer based on an array of high-quality-factor photonic crystal nanocavities, coupled via a planar two-dimensional waveguide. This architecture enables spectral analysis of incident light with resolution as high as the bandwidth of the cavity mode–0.3 nm at 840 nm for our device. The design is easily extended to the visible and deep-infrared spectral ranges. The two-dimensional cavity array can be mated to commercial two-dimensional optical detector arrays, creating a compact and high-resolution spectrometer suitable for a range of applications including materials and chemical analysis.
400%/W second harmonic conversion efficiency in 14 μm-diameter gallium phosphide-on-oxide resonators
2018Optics Express · 67 Zitationen · DOI
Second harmonic conversion from 1550 nm to 775 nm with an efficiency of 400% W<sup>-1</sup> is demonstrated in a gallium phosphide (GaP) on oxide integrated photonic platform. The platform consists of doubly-resonant, phase-matched ring resonators with quality factors Q ∼ 10<sup>4</sup>, low mode volumes V ∼ 30(λ/n)<sup>3</sup>, and high nonlinear mode overlaps. Measurements and simulations indicate that conversion efficiencies can be increased by a factor of 20 by improving the waveguide-cavity coupling to achieve critical coupling in current devices.
Nanotechnology · 63 Zitationen · DOI
We report the observation of field emission (FE) from InP nanocrystals (NCs) epitaxially grown on an array of p-Si nanotips. We prove that FE can be enhanced by covering the InP NCs with graphene. The measurements are performed inside a scanning electron microscope chamber with a nano-controlled W-thread used as an anode. We analyze the FE by Fowler-Nordheim theory and find that the field enhancement factor increases monotonically with the spacing between the anode and the cathode. We also show that InP/p-Si junction has a rectifying behavior, while graphene on InP creates an ohmic contact. Understanding the fundamentals of such nanojunctions is key for applications in nanoelectronics.
Physical review. B, Condensed matter · 56 Zitationen · DOI
The optical emission and dynamics of carriers in Stranski-Krastanow self-organized InP quantum dots embedded in a GaP matrix are studied. InP deposited on GaP (001) using gas-source molecular-beam epitaxy forms quantum dots for InP coverage greater than 1.8 monolayers. Strong photoluminescence from the quantum dots is observed up to room temperature at about 2 eV; photoluminescence from the two-dimensional InP wetting layer is measured at about 2.2 eV. Modeling based on the ``model-solid theory'' indicates that the band alignment for the InP quantum dots is direct and type I. Furthermore, low-temperature time-resolved photoluminescence measurements indicate that the carrier lifetime in the quantum dots is about 2 ns, typical for type-I quantum dots. Pressure-dependent photoluminescence measurements provide further evidence for a type-I band alignment for InP/GaP quantum dots at normal pressure with the GaP X states lying about 30 meV higher than the $\ensuremath{\Gamma}$ states in the InP quantum dots, but indicate that they become type II under hydrostatic pressures of about 1.2 GPa.
Journal of Applied Physics · 47 Zitationen · DOI
The growth, fabrication, and device characterization of InP quantum-dot light-emitting diodes based on GaP are described and discussed. The diode structures are grown on gallium phosphide substrates using gas-source molecular-beam epitaxy and the active region of the diode consists of self-assembled InP quantum dots embedded in a GaP matrix. Red electroluminescence originating from direct band-gap emission from the InP quantum dots is observed at low temperatures.With increasing temperature, however, the emission line shifts to the longer wavelength. The emission light is measured to above room temperature.
Nano Letters · 39 Zitationen · DOI
Generating entangled graph states of qubits requires high entanglement rates with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.
Journal of Crystal Growth · 39 Zitationen · DOI
Sensors and Actuators B Chemical · 36 Zitationen · DOI
Applied Physics Letters · 36 Zitationen · DOI
We demonstrate and characterize continuous wave χ(2) sum-frequency generation in gallium phosphide photonic crystal nanocavities. We use two confined modes of the nanocavity in the wavelength range 1500–1600 nm to enhance conversion efficiency. Our results show that these nanocavities can serve as integrated light sources across a range of wavelengths, and are promising for on-chip upconversion of weak intensity telecommunication wavelengths signals to visible wavelengths.
Applied Physics Letters · 36 Zitationen · DOI
Photoluminescent molecules are coupled to high quality photonic crystal nanocavities. The cavities are fabricated in a gallium phosphide membrane and show resonances from 735 to 860 nm with quality factors up to 12 000. The molecules, which are dispersed in a thin polymer film deposited on top of the cavities, can be selectively positioned onto the location of the cavity by using a lithographic technique, which is easily scalable to arrays of cavities.
Applied Physics Letters · 36 Zitationen · DOI
We describe the growth and optical emission from strained InP quantum dots grown on GaP using gas-source molecular beam epitaxy. Self-organized island formation takes place for InP coverage greater than 1.8 monolayers on the (100) GaP surface. Intense photoluminescence from the dots is peaked at about 2.0 eV, blueshifted by 0.6 eV from the band gap of bulk InP due to strain, quantum size effects, and possibly Ga interdiffusion.
Applied Physics Letters · 35 Zitationen · DOI
The authors report the growth and structural properties of InSb and InSb:N quantum dots on InAs and GaAs substrates. Strain induced self-assembled quantum dots are grown using solid-source molecular beam epitaxy. For improved growth control, they developed a growth technique similar to atomic-layer epitaxial methods. InSb and InSb:N multiple quantum dots formed on both InAs and GaAs. They explain the formation of multiple quantum dots by the anisotropic distribution of strain energy within the quantum dot, the long adatom lifetime during atomic-layer epitaxy, and the low bond energy of InSb.
Physical review. B, Condensed matter · 35 Zitationen · DOI
InP quantum dots grown on (001) InGaP/GaAs exhibit a pronounced size anisotropy with respect to the [110] and $[11\ifmmode\bar\else\textasciimacron\fi{}0]$ directions. This asymmetry leads to a remarkable polarization dependence of photoluminescence spectra and to different elastic relaxation in these directions. The strain distribution is investigated by x-ray diffuse scattering along with respective kinematical simulations using linear elasticity theory. The geometric aspect ratios of island height and island base widths are evaluated with high accuracy and the influence of these ratios on the strain field inside the quantum dots is discussed.
Large-scale GaP-on-diamond integrated photonics platform for NV center-based quantum information
2016Journal of the Optical Society of America B · 34 Zitationen · DOI
We present chip-scale transmission measurements for three key components of a gallium-phosphide (GaP)-on-diamond integrated photonics platform: waveguide-coupled disk resonators, directional couplers, and grating couplers. We also present proof-of-principle measurements demonstrating nitrogen-vacancy (NV) center-emission coupled into selected devices. The demonstrated device performance, uniformity, and yield place the platform in a strong position to realize measurement-based quantum information protocols utilizing the NV center in diamond.
Applied Physics Letters · 33 Zitationen · DOI
We demonstrate a straightforward way to obtain single well-isolated quantum dots emitting in the visible part of the spectrum and characterize the optical emission from single quantum dots using this method. Self-assembled InP quantum dots are grown using gas-source molecular-beam epitaxy over a wide range of InP deposition rates, using an ultralow growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/μm2 is realized. The resulting isolated InP quantum dots embedded in an InGaP matrix are individually characterized without the need for lithographical patterning and masks on the substrate. Such low-density quantum dots show excitonic emission at around 670 nm with a linewidth limited by instrument resolution. This system is applicable as a single-photon source for applications such as quantum cryptography.
ACS Applied Materials & Interfaces · 32 Zitationen · DOI
The epitaxial integration of highly heterogeneous material systems with silicon (Si) is a central topic in (opto-)electronics owing to device applications. InP could open new avenues for the realization of novel devices such as high-mobility transistors in next-generation CMOS or efficient lasers in Si photonics circuitry. However, the InP/Si heteroepitaxy is highly challenging due to the lattice (∼8%), thermal expansion mismatch (∼84%), and the different lattice symmetries. Here, we demonstrate the growth of InP nanocrystals showing high structural quality and excellent optoelectronic properties on Si. Our CMOS-compatible innovative approach exploits the selective epitaxy of InP nanocrystals on Si nanometric seeds obtained by the opening of lattice-arranged Si nanotips embedded in a SiO<sub>2</sub> matrix. A graphene/InP/Si-tip heterostructure was realized on obtained materials, revealing rectifying behavior and promising photodetection. This work presents a significant advance toward the monolithic integration of graphene/III-V based hybrid devices onto the mainstream Si technology platform.
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Stammdaten
Identität, Organisation und Kontakt aus HU-FIS.
- Name
- Dr. rer. nat. Fariba Hatami
- Titel
- Dr. rer. nat.
- Fakultät
- Mathematisch-Naturwissenschaftliche Fakultät
- Institut
- Institut für Physik
- Arbeitsgruppe
- Experimentelle Physik (Elementaranregungen und Transport in Festkörpern)
- Telefon
- +49 30 2093-82196
- HU-FIS-Profil
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- 26.4.2026, 01:05:53