1. Effect of N-Type AlGaN Layer on Carrier Transportation and Efficiency Droop of Blue InGaN Light-Emitting Diodes 1 Sheng-Horng Yen, Miao-Chan Tsai, Meng-Lun Tsai, Yu-Jiun Shen, Ta-Cheng Hsu, and Yen-Kuang Kuo IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 21, NO. 14, JULY 15, 2009 C.C. Shan

2. Outline Introduction Experimental Results and Discussion Conclusion References 2

3. Introduction Reduce the electron leakage current Retards the holes from injecting into the active region. 3

4. Experimental 4 1.2×10 18 cm -3 300 ×300 μm 2 Sapphire Buffer layer n-GaN-4.5μm(5×10 18 cm -3 ) MQW-100nm p-GaN-0.5 μm p-Al 0.15 Ga 0.85 N-2nm u-GaN-1.5 μm 5×10 18 cm -3 n-Al 0.15 Ga 0.85 N

5. Experimental 5 Fig. 1. L-I curves of the LEDs with P-AlGaN and N-AlGaN. Experimental data are presented by green solid dots.

6. Experimental 6 Fig. 2. IQE of the LEDs with P-AlGaN and N-AlGaN.

7. Results and Discussion 7 Fig. 3. (a) Hole and (b) electron concentrations of the LEDs with P-AlGaN and N-AlGaN at 120 mA.