A5026448922- GaN-based semiconductor devices and materials
- Metal and Thin Film Mechanics
- Ga2O3 and related materials
- ZnO doping and properties
- Semiconductor materials and devices
- Semiconductor Quantum Structures and Devices
- Photocathodes and Microchannel Plates
- Digital Holography and Microscopy
- Reproductive System and Pregnancy
- Pregnancy and preeclampsia studies
- Preterm Birth and Chorioamnionitis
- Advanced Fluorescence Microscopy Techniques
- Cognitive Radio Networks and Spectrum Sensing
- Cell Image Analysis Techniques
- Telecommunications and Broadcasting Technologies
- Wireless Communication Networks Research
- Plasma Diagnostics and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Silicon Carbide Semiconductor Technologies
- Nuclear Engineering Thermal-Hydraulics
- Forensic and Genetic Research
- Gas Sensing Nanomaterials and Sensors
- Heat transfer and supercritical fluids
- Microscopic Colitis
- Advanced Wireless Network Optimization
Uppsala University
2024
Punjab Agricultural University
2023
European Molecular Biology Laboratory
2020-2022
Guru Gobind Singh Medical College and Hospital
2014-2022
European Molecular Biology Laboratory
2022
UiT The Arctic University of Norway
2017-2020
Indian Institute of Technology Delhi
2016
Guru Nanak Dev University
2013
Magnolia Optical Technologies (United States)
2005-2006
Polaroid (United States)
1997-2003
We report the growth of InGaN thick films and InGaN/GaN double heterostructures by molecular beam epitaxy at substrate temperatures 700–800 °C, which is optimal for GaN. X-ray diffraction optical absorption studies show phase separation InN InxGal−xN with x>0.3. On other hand, InxGal−xN/GaN no evidence within detection capabilities our methods. These observations were accounted using Stringfellow’s model on separation, gives a critical temperature miscibility GaN–InN system equal to 2457 K.
Blue-violet gallium nitride (GaN) light emitting p-n junctions were grown by the method of electron cyclotron resonance-assisted molecular beam epitaxy. This has been modified to minimize plasma induced defects. Contrary similar devices metalorganic chemical vapor deposition, these do not require any postgrowth annealing activate Mg acceptors in p layer. These turn-on at approximately 3 V and have a spectral emission peaking 430 nm.
Hole concentrations of up to 1019 cm−3 have been reported for GaN:Mg films grown by molecular beam epitaxy without any post-growth treatment. Comparing results from Hall measurements and secondary ion mass spectrometry, we observe doping efficiencies 10% at room temperatures in such p-type material. By hydrogenating above 500 °C, the hole concentration can be reduced an order magnitude. A new photoluminescence line 3.35 eV is observed after this treatment, both unintentionally doped n-type...
We report the intensity dependence of band-gap and midgap photoluminescence in GaN films grown by electron cyclotron resonance (ECR) microwave plasma-assisted molecular beam epitaxy. find that luminescence depends linearly while has a nonlinear on incident light intensity. These data were compared with simple recombination model which assumes density centers 2.2 eV below conduction band edge. The concentration these is higher at power ECR plasma.
The electronic structure of thin-film wurtzite GaN has been studied using a combination soft-x-ray absorption and emission spectroscopies. We have measured the elementally orbitally resolved valence conduction bands by recording Ga $L$ N $K$ spectra. compare x-ray spectra to partial density states from recent ab initio calculation find good overall agreement. confirm that top band is dominated $2p$ whereas they reveal there only weak hybridization between $4s$ states. Surprisingly, we found...
The cnidarian Nematostella vectensis has developed into a powerful model system to study the mechanisms underlying animal development, regeneration, and evolution. However, despite significant progress in molecular genetic approaches this sea anemone, endogenous protein tagging is still challenging. Here, we report robust method for knock using CRISPR/Cas9. As an outcome, generate endogenously tagged proteins that label core components of several cellular apparatus, including nuclear...
Total internal reflection fluorescence (TIRF) microscopy benefits from high-sensitivity, low background noise, photo-toxicity and high-contrast imaging of sub-cellular structures close to the membrane surface. Although, TIRF provides it does not provide quantitative information about morphological features biological cells. Here, we propose an integrated waveguide chip-based label-free phase (QPI). The evanescent field present on top a surface is used excite upright microscope collect...
We report on the growth and doping of GaN by molecular-beam epitaxy c-plane sapphire. find that steps nitridation low-temperature buffer have a significant effect structure, microstructure, defects opto-electronic properties grown films. The electron mobility in Si-doped films was found to be controlled both density ionized impurities dislocations. This result is consistent with model which assumes dislocations introduce acceptor centers. Films were doped p-type Mg carrier concentration up...
We use Raman scattering to obtain a stress map of lateral epitaxy overgrown GaN. Isolated hexagonal islands are grown by selective area overgrowth without seed layer. Stress mapping is obtained from shifts in the E2 phonon. GaN aperture has greatest biaxial compressive stress, ≈0.18 GPa. The region under slightly smaller about 0.15 attribute marked variations A1(LO) phonon intensity spatial free carrier concentration. This found be small and high overgrowth. position-dependent presence lower...
Several important questions in biology require non-invasive and three-dimensional imaging techniques with an appropriate spatiotemporal resolution that permits live organisms to move unconstrained fashion over extended field-of-view. While selective-plane illumination microscopy (SPIM) has emerged as a powerful method observe biological specimens at high spatio-temporal resolution, typical implementations often necessitate constraining sample mounting or lack the required volumetric speed....
In0.09Ga0.91N/GaN and In0.35Ga0.65N/Al0.1Ga0.9N multiquantum well structures (MQW) were grown by molecular beam epitaxy on (0001) sapphire substrates. The thickness of the wells barriers in range 80–120 Å. microstructure these MQW was investigated transmission electron microscopy. room temperature photoluminescence spectra peak at 387 463 nm with full width half maximum 16 28 nm, respectively.
This paper reports the development of aluminum-gallium nitride (AlGaN or Al<sub>x</sub>Ga<sub>1-x</sub>N) photodiode technology for high-operability 256×256 hybrid Focal Plane Arrays (FPAs) solar-blind ultraviolet (UV) detection in 260-280 nm spectral region. These UV FPAs consist a back-illuminated AlGaN p-i-n array, operating at zero bias voltage, bump-mounted to matching silicon CMOS readout integrated circuit (ROIC) chip. The unit cell size is 30×30 μm<sup>2</sup>. arrays were...
This paper presents characterization data, including UV imagery, for 256 × AlGaN Focal Plane Arrays (FPAs). The UV-FPAs have 30 μm2 unit cells, and use back-illuminated arrays of p–i–n photodiodes operating at zero bias voltage. photodiode were fabricated from multilayer films grown by MOCVD on sapphire substrates. Data are also presented individual variable-area diagnostic arrays.
A mode-locked Yb/sup 3+/ fiber laser operating at 980 nm is reported. Using a semiconductor saturable-absorber mirror in incorporating grating-pair dispersive delay line, we obtain reliable self-starting 1.6-ps pulse operation.
An advance multiresolution wavelet based approach for wideband spectrum sensing cognitive radio system is proposed in this paper. Prime focus made on the coarse detection part interweaved system, which unoccupied can be used efficiently by users. Quick and immediate shifting over sensed vacant channel extremely vital a challenging task. To overcome issue, fast efficient technique radios improvising Discrete Wavelet Packet Transform (DWPT) systems. This scheme not only increases speed but...
In pregnancy during an inflammatory condition, macrophages present at the feto-maternal junction release increased amount of nitric oxide (NO) and pro-inflammatory cytokines such as TNF-α INF-γ, which can disturb trophoblast functions outcome. Measurement cellular sub-cellular morphological modifications associated with responses are important in order to quantify extent dysfunction for clinical implication. With this motivation, we investigated morphological, changes externally inflamed...
Submicron spatial resolution photoluminescence is used to assess radiative efficiency and uniformity of GaN/InGaN heterojunctions. Room temperature multiple InGaN quantum wells with GaN barriers fabricated by electron-cyclotron resonance assisted molecular beam epitaxy was measured as a function position on facet perpendicular the layer structure. Our high studies reveal that recombination for 50–60 times more efficient than underlying film.
High temperature annealing of Ni and Pt Schottky diodes on n-GaN has been investigated. Ni/n–GaN Pt/n–GaN were fabricated using ultra high vacuum annealed at various temperatures (200 °C−700 °C) rapid thermal anneal system. It was observed that in case Ni/GaN diodes, the barrier height increases for 200 °C then decreases with increase temperature. For Pt/GaN found to decrease The variation ideality factor is discussed basis interfacial chemical reactions between metal semiconductor.
In today's wireless communication environment, the Radio Frequency spectrum is occupied for different purposes like cellular, Television, military, emergency or satellite communication.The frequency used cellular getting over crowded with increasing number of subscribers and demand high data rate text video transmission, but in other broadcast not utilized efficiently, example Television band, some vacant at instant particular time.The could be communication, means borrowed from Broadcast...