1. Y.Y CHEN

2. Outline Introduction Experiment Results and discussion Conclusion
References

3. Introduction
In general, the light output for a multiple quantum well (MQW) light-emitting diode (LED) depends on the internal quantum efficiency (IQE) and the light extraction efficiency (LEE) . The former case mainly depends on the quality of materials and their heterointerfaces within the active region. In addition, the quality of the layer interfaces below and above the active region would also affect LED performance.

4. Introduction
To achieve a smooth n-GaN surface morphology, a high growth temperature and a V/III (group V-to-group III) molar gas-phase concentration ratio are often adopted.
In addition, the quantum efficiency of LEDs is also dependent on the current spreading effect on the LEDs.
In general, most interests in the topics of current spreading (CS) for the GaN-based LEDs are focused on the p-type top contact layers including transparent conductive oxides.

5. Introduction
Except for the top CS layer, a bottom CS layer positioned between the substrate and the active layer of a LED is also an important issue to further improve the current spreading performance.
In this study, an Si-doped InGaN layer was placed between the n-GaN buffer (i.e., cladding) and the active layers. The InGaN insertion layer plays the role of a current-spreading layer and/or a smoothing layer. The related results which focus on the electrical and optical properties of the fabricated LEDs will be discussed subsequently.

6. carrier concentration
Experiment
LED I
wafers were thinned down to 90μm
Chip size: 250*575μm2
820℃
carrier concentration
1*1018

7. Results and discussion
18.1mW
15.3mW

14. Conclusion
In conclusion, GaN-based blue LEDs using the InGaN insertion layer between the n-type GaN cladding layer and the active layer (InGaN/GaN multiple quantum well) can effectively improve device performances including the endurance of ESD and light output power. Based on the aforesaid chraracterizations,we would like to suggest that the better current spreading effect is the dominant factor for contributing to the improvement of device performance.

15. References
J. K. Sheu, J. M. Tsai, S. C. Shei, W. C. Lai, T. C.Wen, C. H.Kou, Y. K.Su, S. J. Chang, and G. C. Chi, “Low-operation voltage of InGaN/GaN light-emitting diodes with Si-doped Short-period superlattice tunneling contact layer,” IEEE Electron Device Lett., vol. 22, no. 10, pp. 460–462, Oct
E.-H. Park, J. Jang, S. Gupta, I. Ferguson, S.-K. Jeon, J.-G. Lim, J.-S. Lee, C.-H. Kim, and J.-S. Park, “The effect of the last quantum barrier on the internal quantum efficiencyof InGaN-light emitting diode,” Appl. Phys. Lett., vol. 93, p , 2008, and references therein.

16. Thank you for your attention