Enhancement of visible light photodetector performance for ultrafast switching using flower shaped gallium nitride nanostructures

2021 ◽  
Vol 194 ◽  
pp. 113711
Author(s):  
Sanjay Sankaranarayanan ◽  
Prabakaran Kandasamy ◽  
Ramesh Raju ◽  
Saravanan Gengan ◽  
Baskar Krishnan
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
Ultrafast Switching

Site Selective Magneto-Optical Studies of Eu ions in Gallium Nitride

2011 ◽  
Vol 1342 ◽  
Author(s):  
Nathaniel Woodward ◽  
Atsushi Nishikawa ◽  
Yasufumi Fujiwara ◽  
Volkmar Dierolf
Keyword(s):  
Gallium Nitride ◽  
Magnetic Fields ◽  
Visible Light ◽  
Resonant Excitation ◽  
Optical Studies ◽  
G Value ◽  
Site Selective

ABSTRACTWe report site-selective studies of the Zeeman splittings that are observed for magnetic fields up to 6.6T for different Eu incorporation sites in GaN. Utilizing resonant excitation with visible light, we are able to distinguish the site and find for one center (Eu1) a splitting into five components as expected for C3v symmetry. The corresponding g-values are 1.66 and 1.90. The two lines of another center Eu2 each split into two levels corresponding to g-values of 1.9 and 2.84. Most surprisingly a third center, for which only one line is clearly identified, a g-value of 6.16 is found which is larger than can be explained for a 7F2 purely ionic Eu state.

scholarly journals Narrow Linewidth Distributed Bragg Reflectors Based on InGaN/GaN Laser

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 529 ◽  
Author(s):  
Xie ◽  
Li ◽  
Liao ◽  
Deng ◽  
Wang ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
Communication Systems ◽  
Fdtd Method ◽  
Visible Light Communication ◽  
Bragg Reflector ◽  
Duty Ratio ◽  
Light Sources ◽  
Distributed Bragg Reflector ◽  
Dbr Lasers

A variety of emerging technologies, such as visible light communication systems, require narrow linewidths and easy-to-integrate light sources. Such a requirement could be potentially fulfilled with the distributed Bragg reflector (DBR) lasers, which are also promising for the monolithical integration with other optical components. The InGaN/GaN-based surface etched DBR is designed and optimized using the finite-difference-time-domain (FDTD) method to obtain very narrow-band reflectors that can serve as a wavelength filter. The results reveal that the ultimate reflectivity depends on the grating period and duty ratio of the DBR. Based on the design, the DBR lasers with various duty ratios are fabricated, specifically, the 19th, 13th and 3rd order DBR grating with duty ratio set as 50%/75%/95%. The minimum linewidth could be achieved at 0.45 nm from the 19th order grating with a 75% duty ratio. For comparison, the Fabry–Pérot (F–P) based on the same indium gallium nitride/gallium nitride (InGaN/GaN) epitaxial wafer are fabricated. The full width at half maximum (FWHM) of the DBR laser shrank by 65% compared to that of the conventional F–P laser, which might be helpful in the application of the visible light communication system.

Visible light metasurfaces based on gallium nitride high contrast gratings

2016 ◽  
Vol 367 ◽  
pp. 144-148 ◽  
Author(s):  
Zhenhai Wang ◽  
Shumin He ◽  
Qifa Liu ◽  
Wei Wang
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
High Contrast

scholarly journals A review of gallium nitride LEDs for multi-gigabit-per-second visible light data communications

2017 ◽  
Vol 32 (2) ◽  
pp. 023001 ◽  
Author(s):  
Sujan Rajbhandari ◽  
Jonathan J D McKendry ◽  
Johannes Herrnsdorf ◽  
Hyunchae Chun ◽  
Grahame Faulkner ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
Data Communications

scholarly journals Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1487 ◽  
Author(s):  
Peter Griffin ◽  
Tongtong Zhu ◽  
Rachel Oliver
Keyword(s):  
Gallium Nitride ◽  
Visible Light ◽  
Electrochemical Etching ◽  
High Density ◽  
Etching Process ◽  
Bragg Reflectors ◽  
Distributed Bragg Reflectors ◽  
Material Growth ◽  
Low Efficiency ◽  
Uv Leds

Utilising dislocation-related vertical etching channels in gallium nitride, we have previously demonstrated a simple electrochemical etching (ECE) process that can create layered porous GaN structures to form distributed Bragg reflectors for visible light at wafer scale. Here, we apply the same ECE process to realise AlGaN-based ultraviolet distributed Bragg reflectors (DBRs). These are of interest because they could provide a pathway to non-absorbing UV reflectors to enhance the performance of UV LEDs, which currently have extremely low efficiency. We have demonstrated porous AlGaN-based UV DBRs with a peak reflectance of 89% at 324 nm. The uniformity of these devices is currently low, as the as-grown material has a high density of V-pits and these alter the etching process. However, our results indicate that if the material growth is optimised, the ECE process will be useful for the fabrication of UV reflectors.

Single nanoflake-based PtSe2 p–n junction (in-plane) formed by optical excitation of point defects in BN for ultrafast switching photodiodes

2021 ◽  
Vol 9 (1) ◽  
pp. 199-207
Author(s):  
Sikandar Aftab ◽  
Ms Samiya ◽  
Hafiz Mansoor Ul Haq ◽  
Muhammad Waqas Iqbal ◽  
Muhammad Hussain ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Visible Light ◽  
Point Defects ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Optical Excitation ◽  
Van Der Waals Heterostructures ◽  
Ultrafast Switching

Here, novel lateral PtSe2 p–n junctions are fabricated based on the PtSe2/BN/graphene (Gr) van der Waals heterostructures upon the illumination of visible light via the optical excitation of the mid-gap point defects in hexagonal boron nitride (h-BN).

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

Photocatalyst-free decarboxylative aminoalkylation of imidazo[1,2-a]pyridines with N-aryl glycines enabled by visible light

2019 ◽  
Vol 6 (21) ◽  
pp. 3693-3697 ◽  
Author(s):  
Jiu-Jian Ji ◽  
Zhi-Qiang Zhu ◽  
Li-Jin Xiao ◽  
Dong Guo ◽  
Xiao Zhu ◽  
...  
Keyword(s):  
Visible Light

A novel, green and efficient visible-light-promoted decarboxylative aminoalkylation reaction of imidazo[1,2-a]pyridines with N-aryl glycines has been described.

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