Interdigital Structure Enhanced the Current Spreading and Light Output Power of GaN-Based Light Emitting Diodes

In this manuscript, blue light emitting diodes (LEDs) with comb-shaped mesa and interdigital electrodes structure based on gallium nitride (GaN) are presented. This kind of LEDs have showed higher light output power and more efficient current spreading, comparing with a reference large-area LED. For the optimized LED structure, the light output power and external quantum efficiency, considering the actual emission area, reach to 600 mW and 73% at a forward current of 350 mA. The experimental results are consistent with the predictions of current expansion equations. The comb-shaped mesa structure decreases the total internal reflection (TIR) and the interdigital electrodes improve the current crowding effect, as validated from the electrical and optical tests. Therefore, the efficiency and reliability of the LED devices have been significantly enhanced by reducing the transverse current path. This work should be of guiding significance for structural design of large-area/high-power optoelectronic devices.

[1]  Hoi Wai Choi,et al.  High extraction efficiency InGaN micro-ring light-emitting diodes , 2003 .

[2]  D. Díaz,et al.  Wet‐Chemical Etching of GaN: Underlying Mechanism of a Key Step in Blue and White LED Production , 2018 .

[3]  D. H. Mash,et al.  Light-emitting diodes , 1977, Nature.

[4]  Umesh K. Mishra,et al.  Current status and scope of gallium nitride-based vertical transistors for high-power electronics application , 2013 .

[5]  Chien-Ju Chen,et al.  Fabrication and Characterization of Active-Matrix $960\times540$ Blue GaN-Based Micro-LED Display , 2019, IEEE Journal of Quantum Electronics.

[6]  Jian-jang Huang,et al.  Interactions of Diffraction Modes Contributed From Surface Photonic Crystals and Nanoholes in a GaN-Based Light-Emitting Diode , 2011, Journal of Lightwave Technology.

[7]  Wei Liu,et al.  Low thermal-mass LEDs: size effect and limits. , 2014, Optics express.

[8]  C. Dhanavantri,et al.  Performances of p-side down vertical InGaN/GaN blue light-emitting diodes with chip size , 2017 .

[9]  R. Horng,et al.  Effects of Mesa Size on Current Spreading and Light Extraction of GaN-Based LEDs , 2015, Journal of Display Technology.

[10]  A. Podoltsev,et al.  Current crowding effect on the ideality factor and efficiency droop in blue lateral InGaN/GaN light emitting diodes , 2010 .

[11]  Hyunsang Hwang,et al.  Lateral current transport path, a model for GaN-based light-emitting diodes: Applications to practical device designs , 2002 .

[12]  Gregory Triplett,et al.  Thermal and spectral analysis of self-heating effects in high-power LEDs , 2010 .

[14]  Nadarajah Narendran,et al.  Spectral and luminous efficacy change of high-power LEDs under different dimming methods , 2006, SPIE Optics + Photonics.

[15]  Zi-hui Zhang,et al.  Enhanced the Optical Power of AlGaN-Based Deep Ultraviolet Light-Emitting Diode by Optimizing Mesa Sidewall Angle , 2018, IEEE Photonics Journal.

[16]  Sungmin Hwang,et al.  A Method for Current Spreading Analysis and Electrode Pattern Design in Light-Emitting Diodes , 2008, IEEE Transactions on Electron Devices.

[17]  Contact-geometry engineering in a circular light-emitting diode (LED) for improved electrical and optical performances , 2013 .

[18]  M. G. Craford.  Visible LEDs: the trend toward high-power emitters and remaining challenges for solid state lighting , 2002, SPIE Optics + Photonics.

[19]  Yongjin Cho,et al.  Blue (In,Ga)N light-emitting diodes with buried n+–p+ tunnel junctions by plasma-assisted molecular beam epitaxy , 2018, Japanese Journal of Applied Physics.

[20]  Wen-Chau Liu,et al.  Enhanced Light Extraction of GaN-Based Light-Emitting Diodes With a Hybrid Structure Incorporating Microhole Arrays and Textured Sidewalls , 2018, IEEE Transactions on Electron Devices.

[21]  Shui-Jinn Wang,et al.  Enhanced light extraction of GaN-based vertical LEDs with patterned trenches and nanostructures , 2017 .

[22]  G. Verzellesi,et al.  Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies , 2013 .

[23]  Jong Kyu Kim,et al.  Solid-State Light Sources Getting Smart , 2005, Science.

[24]  Yuh-Renn Wu,et al.  Study on the Current Spreading Effect and Light Extraction Enhancement of Vertical GaN/InGaN LEDs , 2012, IEEE Transactions on Electron Devices.

[25]  Erdan Gu,et al.  Size-dependent efficiency and efficiency droop of blue InGaN micro-light emitting diodes , 2012 .

[26]  N. Cheung,et al.  Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off , 1999 .

[27]  Heon Lee,et al.  Improvement of photon extraction efficiency of GaN-based LED using micro and nano complex polymer structures , 2011, Nanoscale research letters.

[28]  A. Shaligram,et al.  Impact of current controlled dimming on spectral characteristics of high power LEDs , 2019, Optics & Laser Technology.

[29]  E. F. Schubert,et al.  Current crowding in GaN/InGaN light emitting diodes on insulating substrates , 2001 .

[30]  M. Lee,et al.  Light-emitting diodes with surface gallium nitride p–n homojunction structure formed by selective area regrowth , 2019, Scientific Reports.

[31]  P. Hinze,et al.  Suppression of nonradiative recombination by V-shaped pits in GaInN/GaN quantum wells produces a large increase in the light emission efficiency. , 2005, Physical review letters.

[32]  Jong Kyu Kim,et al.  An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission , 2016, Scientific Reports.

[33]  S. Karpov,et al.  Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study , 2018, Photonics.

[34]  Xian-An Cao,et al.  High-power and reliable operation of vertical light-emitting diodes on bulk GaN , 2004 .

[35]  Weidong Zhou,et al.  GaN-on-Si resonant-cavity light-emitting diode incorporating top and bottom dielectric distributed Bragg reflectors , 2019, Applied Physics Express.

[36]  Enhanced Light Extraction in GaN-Based Light Emitting Diodes Fabricated with Increased Mesa Sidewalls , 2010 .

[37]  Hyunsang Hwang,et al.  Modeling of a GaN-based light-emitting diode for uniform current spreading , 2000 .

[38]  E. Fred Schubert,et al.  Elimination of total internal reflection in GaInN light-emitting diodes by graded-refractive-index micropillars , 2008 .

[39]  Jing Li,et al.  III-nitride blue microdisplays , 2001 .

[40]  Tae Geun Kim,et al.  Improved optical and electrical properties of GaN-based micro light-emitting diode arrays , 2018, Current applied physics.