1. Temperature dependence of performance of InGaN/GaN MQW LEDs
YC Chiang

2. Outline Motive Temperature dependence Results and Discussion
Different MQW Structures
Different Indium Compositions
Results and Discussion
Conclusions
Reference

3. Motive The impact of temperature on the LED for a great
Hot-Cold effect

4. Experimental
Results and Discussion
Conclusions

5. p-AlGaN重要性
Add a layer of LED are now p-AlGaN electron blocking layer to block electron overflow.
The disadvantage is that Vf rise will increase the resistance

6. Experimental Chip size：300 x 300 μm2 Without p-AlGaN：LED A
p-contact
Without p-AlGaN：LED A
With p-AlGaN：LED B
ITO
p-GaN
p-AlGaN
five pairs
In0.25Ga0.75N/GaN
n-contact
n-GaN
n-GaN
un-doped GaN
30nm
buffer layer
Sapphire

7. Results and Discussion
Why?
可增加電子侷限犧牲的是Vf上升
Figure 1. I-V characteristics of the LEDs with and without a p-AlGaN cladding layer above InGaN/GaN MQW structure.

8. Results and Discussion
避開AlGaN會影響波長的現象
微觀去看其實波長飄蠻多的
Figure 2. (a) Electroluminescence spectra for two LEDs at room temperature. (b) Variation of dominant peak wavelength of two LEDs as a function of the temperature.

9. Al 含量對極化的影響

10. Results and Discussion
可增加電子侷限效應
Figure 3. Output powers of two unpackaged LEDs as a function of injection current at room temperature.

11. Results and Discussion
因為多了一層電子阻擋層使得在溫度上升時有良好的店子侷限能力
Figure 4. Normalized output intensities and fitted lines of two LEDs as a function of the temperature at a constant current of 20 mA.

12. Conclusions
The output power for an LED with a p-AlGaN electron blocking layer above the MQWs dropped more slowly than that of LED without this layer due to a reduction in overflowing electrons from quantum well active region.
Increased radiation recombination in the active region due to better carrier confinement for the p-AlGaN cladding layer.