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We present the enhancement of wall-plug efficiency in vertical InGaN/GaN light-emitting diodes (V-LEDs) by improved current spreading with a novel Al2O3 current blocking layer (CBL). The Al2O3 CBL deposited by electron-beam evaporation shows high transmittance and good corrosion resistance to acidic solutions. V-LEDs with an Al2O3 CBL show similar light output power but lower forward voltage as compared to those with a SiO2 CBL deposited by plasma-enhanced chemical vapor deposition. As a result, the wall-plug efficiency of V-LEDs with an Al2O3 CBL at 500 mA was improved by 5% as compared to those with a SiO2 CBL, and by 19% as compared to those without a CBL.
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http://dx.doi.org/10.1364/OE.20.00A287 | DOI Listing |
Sensors (Basel)
July 2025
Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.
In this work, we present a high-performance tapered quantum cascade laser (QCL) designed to achieve both high output power and low divergence angle. By integrating a tapered waveguide with a Fabry-Perot structure, significant improvements of tapered QCL devices in both output power and beam quality are demonstrated. The optimized 50 µm wide tapered QCL achieved a maximum output power of 2.
View Article and Find Full Text PDFThis study introduces innovative structural enhancements in deep ultraviolet LEDs (DUV-LEDs) to optimize Performance. By implementing a 46.9° sloped mesa sidewall, we have designed what we believe to be two novel structures: an n-electrode hole structure that extends the active region and an interrupted mesa structure that significantly enlarges the sidewall area.
View Article and Find Full Text PDFAdv Mater
August 2025
State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China.
AlGaN-based ultraviolet (UV) light emitters in the range of 280-320 nm (UVB band) show irreplaceable prospects in the field of medical care, but suffer from a low-efficiency issue known as the "UVB gap." This issue stems from the large lattice mismatch between low-Al-content AlGaN and AlN, which causes the AlGaN epilayer to endure a significant compressive stress during structural stacking, resulting in dislocation multiplication and surface roughening, and thus seriously deteriorating the device performance. Herein, a lattice-engineered architecture through surface pretreatment is proposed, by which dense and discrete nanocrystalline graphite masks, formed by the decomposition of metal organics, are introduced to bring about controllable epitaxial lateral overgrowth and consequent stress.
View Article and Find Full Text PDFLight Sci Appl
July 2025
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL, 60208, USA.
Quantum cascade lasers (QCLs) are unipolar quantum devices based on inter-sub-band transitions. They break the electron-hole recombination mechanism in traditional semiconductor lasers, overcome the long-lasting bottleneck which is that the emission wavelength of semiconductor laser is completely dependent on the bandgap of semiconductor materials. Therefore, their emission wavelength is able to cover the mid-infrared (mid-IR) range and the "Terahertz gap" that is previously inaccessible by any other semiconductor lasers.
View Article and Find Full Text PDFWe report on the use of ultrathin low-coverage p-GaN hole injection islands on the top surface to improve the light extraction in UV LEDs, resulting in world-record UVB AlGaN UV LEDs emitting at 300 and 310 nm. With the optimization of the p-GaN island density, size, thickness, and doping, we demonstrated a 300 nm emitting device with a peak continuous wave (CW) external quantum efficiency (EQE) of 18.9%, a peak CW wall plug efficiency (WPE) of 16.
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