Use different substrate for InGaN-GaN LED

陳詠升

Outline

• Introduction

• Experiment

• Results and Discussion

• Conclusion

• References

High brightness GaN vertical light emitting diodes on metal alloyed substrate for general lighting application

Chuong Anh Trana,, Chen-Fu Chub, Chao-Chen Chengb, Wen-Huan Liub, Jiunn-Yi Chub,Hao-Chun Chengb, Feng-Hsu Fanb, Jui-Kang Yenb, Trung Doana

Introduction

• These LEDs exhibit many limitations as it hardly sustains high current injection and its efficiency drops significantly at higher temperature.

• Report on mass production realization of GaN-based vertical light emitting diodes on metal alloyed substrate.

Experiment

Fig. 1. The schematic diagram and comparison of GaN LEDs on sapphire substrate and GaN VLEDMS.

Experiment

Fig. 2. A schematic cross-section diagram of VLED on metal alloyed substrate.

p-GaN

n-GaN

n-donding pad

Reflector

Passivation

Pattemed surface

MQW

Results and Discussion

Fig. 3. The current–voltage (I–V) characteristics for the VLEDMS andthe conventional LEDs on sapphire.

3.2V

3.4V

Results and Discussion

Fig. 4. The comparison of the light output power–current (L–I)characteristics for the VLEDMS and the conventional LEDs on sapphire.

Results and Discussion

Fig. 5. The scaling effect for the VLEDMS and the conventional LED onsapphire. The efficiency was normalized to the chip size of 350 μm withfixed forward current density.

Conclusion

• Very low serial dynamic resistance, low operation voltage,excellent heat dissipation, and good reliability were obtained.

• An efficiency of 70 lumens/W or better was achieved, rendering the VLEDMS very suitable for general lighting application.

References

• Chuong Anh Trana,, Chen-Fu Chub, Chao-Chen Chengb, Wen-Huan Liub, Jiunn-Yi Chub,Hao-Chun Chengb, Feng-Hsu Fanb, Jui-Kang Yenb, Trung Doana aSemiLEDs Corp., 1080 S. Milpitas Blvd. Milpitas, California 95035, USA bSemi-Photonics, 8F, No.13, Ke-Jung Rd., Chunan Site, Hsinchu Science Park, Hsinchu, Taiwan “High brightness GaN vertical light emitting diodes on metal alloyed substrate for general lighting application”

• Y.C. Lin, S.J. Chang, Y.K. Su, T.Y. Tsai, C.S. Chang, S.C. Shei, C.W.Kuo, S.C. Chen, Solid-State Electron. 47 (2003) 849.

Performance of InGaN–GaN LEDs Fabricated UsingGlue Bonding on 50-mm Si Substrate

Wei Chih Peng and YewChung Sermon Wu

Introduction

• High brightness GaN-based light-emitting diodes(LEDs) have attracted considerable attention for their versatile applications in mobile phones, full-color displays, and lighting.

Experiment

Fig. 1. (a) Schematic illustration of the vertical InGaN LED structure.(b) Scanning electron miscroscope (SEM) image of roughened surface.

Experiment

Fig. 2. (a) Image of an InGaN LED wafer bonded on a 50-mm diameter Sisubstrate. Wafer was successfully cut into isolated devices with an area of300×300 μm2 . (b) SEM image of the cross section of the LED structure afterdicing process.

Results and Discussion

Fig. 3. Performances of vertical and conventional InGaN LEDs. (a) I–Vcharacteristics. (b) Effects of injection current on the luminous intensity.

Results and Discussion

(c) Effects of injection current on the light output. (d) Peak spectral wavelength as a function of dc drives current.

Results and Discussion

Fig. 4. Radiation patterns of (a) sapphire-based LEDs and (b) vertical InGaN LEDs.

Conclusion

• This bonding method enabled the emission of light from the vertical InGaN LED device to be improved such that a single electrode could be used and the light could be reflected downward using a mirror and rougher n-GaN surface. Hence, the light output of the vertical LED chip is 20% greater than that of conventional sapphire-substrate LEDs at 20 mA.

• The vertical LEDs could be operatedat a much higher injection forward current (280 mA) than sapphire-substrate LEDs (180 mA) because the sapphire substrate was replaced with a Si substrate.

References

• Y. K. Song, M. Diagne, H. Zhou, A. V. Nurmikko, C. Carter-Coman, R.S. Kern, F. A. Kish, and M. R. Krames, “A vertical injection blue light emitting diode in substrate separated InGaN heterostructures,” Appl.Phys. Lett., vol. 74, pp. 3720–3722, 1999.

• Wei Chih Peng and YewChung Sermon Wu” Performance of InGaN–GaN LEDs Fabricated Using Glue Bonding on 50-mm Si Substrate”