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Nitride light-emitting diodes T Mukai, S Nagahama, N Iwasa, M Senoh and T Yamada JOURNAL OF PHYSICS: CONDENSED MATTER YC Chiang 1 Outline Motive Experiments Blue LED Green LED Amber LED InGaN active layer AlInGaP active layer UV LED Results and discussion Conclusion Reference 2 Motive In the discussion of different currents at room temperature electroluminescence Discussed under the same current in different temperature electroluminescence Discuss the different structure of threading dislocation 3 Experiments(1/5) <Blue> Ni/Au 0.5μm 700˚C 0.15μm 1020˚C 300Å 800˚C <doped Zn> 0.15μm 1020˚C Ti/Al 4μm 1020˚C 300Å 510˚C Figure 1. The structure of the InGaN/AlGaN double-heterostructure blue LEDs 4 Experiments(2/5) <Green> Ni/Au 0.5μm 30Å 1000Å Ti/Al 4μm 1020˚C 300Å 550˚C Figure 2. The structure of green SQW LEDs. 5 Experiments(3/5) <Amber> p-Electrode <Ni/Au> p-GaN < 0.2μm > p-Al0.2Ga0.8N < 300Å> InGaN <25Å> undoped GaN < 400Å> <Current Spreading Layer> AlInGaP n-Electrode <Ti/Al> n-GaN < 3.3μm > GaN buffer <300Å 550˚C> undoped GaN <0.7μm> Sapphire Substrate GaAs Substrate (For AlInGaP ) Figure 3. The structure of Amber SQW LEDs. 6 Experiments(4/5) <UV> p-Electrode <Ni/Au> p-GaN < 0.2μm > indium composition of the InGaN well layer is nearly zero p-Al0.2Ga0.8N < 300Å> InGaN <25Å> n-Electrode <Ti/Al> n-GaN < 3.3μm > GaN buffer <300Å 550˚C> Sapphire Substrate Figure 4. The structure of UV LEDs. 7 Experiments(5/5) Wavelength(nm) FWHM(nm) External quantum efficiency(EQE) @20mA Blue LED <doped Zn> 450 70 (10~40mA) 2.7% 1500μW SQW Blue LED 450 20 9.1% 5mW SQW Green LED 520 30 6.3% 3mW Amber LED 594 50 ~ ~ UV LED 380 ~ ~ ~ Output power (mW) @20mA 8 Results and discussion(1/9) In 含量少 點我 比較 1.較差的結晶品質 2.Lattice mismatch 3.Thermal expansion coefficient(Well 與Barrier之間) Figure 5. The output power of (a) blue and (b) green SQW LEDs as functions of the forward current. 9 Results and discussion(2/9) ∆ Ec 之 差 ， 反 應 侷 限能力的好壞 1.4mW 0.66mW 25 Figure 6. The output power of amber InGaN and AlInGaP LEDs as functions of the ambient temperature from −30 ˚C to +80 ˚C. The output power of each LED was normalized to 1.0 at 25 ˚C. 10