scholarly journals On the mechanism of carrier recombination in downsized blue micro-LEDs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Po-Wei Chen ◽  
Po-Wen Hsiao ◽  
Hsuan-Jen Chen ◽  
Bo-Sheng Lee ◽  
Kai-Ping Chang ◽  
...  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Passivation Layer ◽  
Electroluminescence Spectrum ◽  
Direct Writing ◽  
Emission Performance ◽  
Carrier Recombination ◽  
Free Process ◽  
Led Array ◽  
Chip Size

AbstractThe mechanism of carrier recombination in downsized μ-LED chips from 100 × 100 to 10 × 10 μm2 on emission performance was systemically investigated. All photolithography processes for defining the μ-LED pattern were achieved by using a laser direct writing technique. This maskless technology achieved the glass-mask-free process, which not only can improve the exposure accuracy but also save the development time. The multi-functional SiO2 film as a passivation layer successfully reduced the leakage current density of μ-LED chips compared with the μ-LED chips without passivation layer. As decreasing the chip size to 10 × 10 μm2, the smallest chip size exhibited the highest ideality factor, which indicated the main carrier recombination at the high-defect-density zone in μ-LED chip leading to the decreased emission performance. The blue-shift phenomenon in the electroluminescence spectrum with decreasing the μ-LED chip size was due to the carrier screening effect and the band filling effect. The 10 × 10 μm2 μ-LED chip exhibited high EQE values in the high current density region with a less efficiency droop, and the max-EQE value was 18.8%. The luminance of 96 × 48 μ-LED array with the chip size of 20 × 20 μm2 exhibited a high value of 516 nits at the voltage of 3 V.

Effects of high current density on lead-free solder joints of chip-size passive SMD components

2018 ◽  
Vol 30 (2) ◽  
pp. 74-80 ◽  
Author(s):  
Attila Geczy ◽  
Daniel Straubinger ◽  
Andras Kovacs ◽  
Oliver Krammer ◽  
Pavel Mach ◽  
...  
Keyword(s):  
Current Density ◽  
Solder Joints ◽  
High Current Density ◽  
Lead Free ◽  
Lead Free Solder ◽  
High Current ◽  
Chip Size ◽  
Free Solder

scholarly journals Study on Low-Temperature Emission Performance of Scandate Cathode with Micro-Blade-Type Arrays

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 100
Author(s):  
Zhipeng Lu ◽  
Shengyi Yin ◽  
Zhaochuan Zhang ◽  
Feng Ren ◽  
Xinping Lv
Keyword(s):  
Low Temperature ◽  
Electric Field ◽  
Current Density ◽  
Electron Emission ◽  
High Current Density ◽  
Field Enhancement ◽  
Enhancement Effect ◽  
High Electron ◽  
Emission Performance ◽  
Scandate Cathode

In order to meet the requirements of high-frequency vacuum electronic devices with small size, high current density, and low working temperature, a kind of porous tungsten scandate cathode with micro-blade-type arrays was developed. The micro-blade-type arrays were fabricated by laser engraving technology. Subsequently, the cathode was prepared by a vacuum copper removal process and impregnated with active substances at high temperature. Experimental results show that the cathode exhibits excellent low-temperature electron emission performance and that the maximum pulse electron emission current density reaches 81.18 A/cm2 at 800 °C. The cathode also shows apparent combined thermal-field emission characteristics. Further analysis shows that a high electric field strength plays an important role in the electron emission of the scandate cathode. By virtue of the electric field enhancement effect formed by the fabricated micro-blade-type arrays on the cathode surface, the prepared cathode achieves high electron emission capacity.

scholarly journals Study on the Effect of Size on InGaN Red Micro-LEDs

2021 ◽  
Author(s):  
Ray-Hua Horng ◽  
Chun-Xin Ye ◽  
Po-Wei Chen ◽  
Daisuke Iida ◽  
Kazuhiro Ohkawa ◽  
...  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Light Emitting Diode ◽  
Blue Shift ◽  
Injection Current ◽  
Emission Wavelength ◽  
Direct Writing ◽  
Light Emitting ◽  
Full Color ◽  
Injection Current Density

Abstract In this research, five sizes (100⊆100, 75⊆75, 50⊆50, 25⊆25, 10⊆10 µm2) of InGaN red micro-light emitting diode (LED) dies are produced using laser-based direct writing and maskless technology. It is observed that with increasing injection current, the smaller the size of the micro-LED, the more obvious the blue shift of the emission wavelength. When the injection current is increased from 0.1 to 1 mA, the emission wavelength of the 10×10 µm2 micro-LED is shifted from 617.15 to 576.87 nm. The obvious blue shift is attributed to the stress release and high current density injection. Moreover, the output power density is very similar for smaller chip micro-LEDs at the same injection current density. This behavior is different from AlGaInP micro-LEDs. The sidewall defect is more easily repaired by passivation, which is similar to the behavior of blue micro-LEDs. The results indicate that the red InGaN epilayer structure provides an opportunity to realize the full color LEDs fabricated by GaN-based LEDs.

Demonstration of SiC-MOSFET Embedding Schottky Barrier Diode for Inactivation of Parasitic Body Diode

2017 ◽  
Vol 897 ◽  
pp. 477-482 ◽  
Author(s):  
Shiro Hino ◽  
Hideyuki Hatta ◽  
Koji Sadamatsu ◽  
Yuichi Nagahisa ◽  
Shigehisa Yamamoto ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
High Voltage ◽  
Current Density ◽  
Specific Resistance ◽  
High Current Density ◽  
Reverse Current ◽  
The Body ◽  
High Current ◽  
Additional Doping ◽  
Chip Size

External Schottky barrier diodes (SBD) are generally used to suppress the conduction of the body diode of MOSFET. A large external SBD is required for a high voltage module because of its high specific resistance, while the forward voltage of SBD should be kept smaller than the built-in potential of the body diode. Embedding SBD into MOSFET with short cycle length increases maximum source-drain voltage where body diode remains inactive, resulting in high current density of SBD current. We propose a MOSFET structure where an SBD is embedded into each unit cell and an additional doping is applied, which allows high current density in reverse operation without any activation of body diode. The proposed MOSFET was successfully fabricated and much higher reverse current density was demonstrated compared to the external SBD. We can expect to reduce total chip size of high voltage modules using the proposed MOSFET embedding SBD.

Fabrication of Al Micro-Coil and Loop by Utilizing Electromigration

2008 ◽  
Author(s):  
Yuxin Sun ◽  
Masumi Saka
Keyword(s):  
Substrate Temperature ◽  
Current Density ◽  
High Current Density ◽  
High Substrate Temperature ◽  
Transverse Force ◽  
Passivation Layer ◽  
High Current ◽  
High Substrate

Aluminum micro-coil and micro-loop have been fabricated by utilizing electromigration. In a passivated Al line with a slit at the anode end, atoms accumulated before the slit due to high current density and high substrate temperature are released from the pre-introduced holes in the passivation layer, and form micro-fibers owing to crystallization. The fibers are rotated under the existence of the transverse force induced by the tilted holes during their growth, and the micro-coil and micro-loop are fabricated.

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

Three-dimensional porous copper-decorated bismuth-based nanofoam for boosting electrochemical reduction of CO2 to formate

2021 ◽  
Author(s):  
Yingchun Zhang ◽  
Changsheng Cao ◽  
Xintao Wu ◽  
Qi-Long Zhu
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Three Dimensional ◽  
Co2 Reduction ◽  
Reduction Reaction ◽  
High Current ◽  
Porous Copper ◽  
Reduction Of Co2 ◽  
Co2 Reduction Reaction ◽  
Wide Potential

Bismuth (Bi)-based nanomaterials are considered as the promising electrocatalysts for electrocatalytic CO2 reduction reaction (CO2RR), but it is challenging to achieve high current density and selectivity in a wide potential...

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