專題研討 ( 二 )Electron-Blocking-Layer, n-EBL

Hole-Blocking-Layer, HBL

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　碩研電子一甲　　　　　　　　　　　　　　　　　 MA230102 　　　　　　　　　　　　　　　楊書瑋　　　　　　　　　　　　　　　　　　　　　　　　　　

2Jeff Yang

Effect of Polarization-Matched n-Type AlGaInN Electron-Blocking Layer on the Optoelectronic

Properties of Blue InGaN Light-Emitting DiodesYun Li, You Gao, Miao He, Jun Zhou, Yan Lei, Li Zhang, Kebao Zhu,

and Yulong Chen

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Outline• Introduction• Experiment• Result and Discussion• Conclusion

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Introduction• Conventional p-type electron- blocking layer (EBL) can be used a

solution to reduce the electron leakage current. However, the p-type EBL also impeded the injection of holes into the active region.

• In this paper, we study the performances of blue InGaN LEDs by using a polarization-matched n-type AlGaInN (N-AlGaInN) EBL to replace p-AlGaInN EBL, p-AlGaInN EBL and n-AlGaN EBL in the active region.

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Chip Size: 300*300 μm2

• Fig. 1. Schematic diagram of InGaN LED structures with P-AlGaInN, N-AlGaN and N-AlGaInN EBL.

Experiment

Sample comparingLEDI P-Al0.38Ga0.46In0.16N

LEDII N-Al0.15Ga0.85N

LEDIII N-Al0.38Ga0.46In0.16N

DetailBuffer 50nm-thickMQW 5-pairs Barrier-10nm*6

Well-5nm*5p-GaN 250nm

6• Fig. 6. Band diagrams and quasi-Fermi levels of the LEDs with: (a) P-AlGaInN, (b) N-AlGaInN, and (c) N-AlGaN layers at 180 mA.

Result and Discussion

7• Fig. 4. (a) Electron and (b) hole concentrations of the LEDs with P-AlGaInN, N-AlGaInN and P-AlGaN EBLs at 180 mA.

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Conclusion• The simulation results show that the N-AlGaInN

EBL is a best candidate the concentration of electrons and holes within the active region of the LEDs with a N-AlGaInN EBL are more uniform, and the electron leakage current is also dramaticlly reduced.

Jeff Yang

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Outline• Introduction• Experiment• Result and Discussion• Conclusion

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Introduction• Recently published studies point out that the electron

confinement by a typical AlGaN EBL is not sufficiently effective to solve the efficiency droop problem. Furthermore, the use of AlGaN EBL can cause some undesired effects such as prohibiting the injection efficiency of holes into the active region.

• In this study, the characteristics of the nitride-based blue LED without an EBL are analyzed. We have discussed the advantages of the LED without an EBL, when compared with those of the similar LED with an AlGaN HBL. We have also investigated the optical and electrical properties of the LEDs with undoped or p-type doped GaN barriers when no EBL is used.

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Experiment

Chip Size: 300*300um

NO. EBL / Thickness / Concentration

MQW 4pairs Barrier variation

A P-Al0.15Ga0.85N / 20nm / 7E17GaN15nm / In0.2Ga0.8N2.2nm

First Barrier (n-5E18)Last Barrier (p-7E17)

u-Barrier

B * u-Barrier

C * p-Barrier (3E17)

D N-Al0.07Ga0.93N / 20nm / 5E18 P-Barrier (3E17)

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Fig. 3. Energy band diagrams of u-GaN barrier LEDs (a) with an AlGaN EBL and (b) without an EBL at 150 mA.

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Fig. 5. (a) Hole and (b) electron concentrations of the non-EBL p-GaNbarrier LEDs with and without a HBL around the active region at 150 mA.

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Fig. 6. (a) EL spectra at 150 mA and (b) IQE versus injection current forthe LEDs of the four structures.

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Conclusion The use of the p-type barriers can effectively

suppress the spillover of electrons out of the active region, as well as increase the hole concentration. The insertion of the HBL can enhance the hole confinement. the efficiency droop of the new structure is markedly improved.

Reference• Effect of electron blocking layer on efficiency droop in InGaN/GaN multiple quantum well light-

emitting diodes Sang-Heon Han, Dong-Yul Lee, Sang-Jun Lee, Chu-Young Cho, Min-Ki Kwon, S. P. Lee, D. Y. Noh,

Dong- Joon Kim, Yong Chun Kim, and Seong-Ju Park

• Hole Injection and Electron Overflow Improvement in 365nm Light-Emitting Diodes by Band-Engineering Electron Blocking Layer

Yi-Keng Fu1, Yu-Hsuan Lu2, Rong Xuan1;3, Jenn-Fang Chen3, and Yan-Kuin Su2

• Advantages of Blue LEDs With Graded-Composition AlGaN/GaN Superlattice EBL Bing-Cheng Lin, Kuo-Ju Chen, Hau-Vei Han, Yu-Pin Lan, Ching-Hsueh Chiu, Chien-Chung Lin, Member,

IEEE, Min-Hsiung Shih, Member, IEEE, Po-Tsung Lee, and Hao-Chung Kuo, Senior Member, IEEE

• http://jys.gmu.cn/wlx/upload/2013_06/13060712577286.ppt 氣體分子極化率的量測 • http://www.twwiki.com/wiki/%E9%9D%9C%E9%9B%BB%E5%A0%B4 靜電場• http://zh.wikipedia.org/zh-tw/%E9%9B%BB%E6%A5%B5%E5%8C%96 電極化 17

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