ssl lab. ssl lab. solid state lighting lab. southern taiwan university 1 adviser : hon kuan adviser...

SSL Lab.

Solid State Lighting Lab.Southern Taiwan University

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Adviser : Hon Kuan

Wen-Cheng Tzou

Reporter:Bo-Jun Liu

Southern Taiwan University

Effect of an electron blocking layer on the piezoelectric field in InGaN/GaN multiple

quantum well light-emitting diodes

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OUTLINE

Introduction

Experiments

Result and Discussion

Conclusion

References

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INTRODUCTION

The effect of an electron blocking layer (EBL) on the piezoelectric field in InGaN/GaN multiple quantum well (MQW).

Electric-field-dependent ER measurements showed an enhanced piezoelectric field in LEDs with a p-AlGaN EBL compared with LEDs without EBL.

SSL Lab.


Experiments

InGaN/GaN MQW LEDs were grown on a (0001) patterned sapphire substrate using metal organic chemical vapor deposition.

The structures of the LEDs consisted of 2.0 lm thick undoped GaN, 3.0-lm thick Si-doped n-GaN, and 5 pairs of InGaN/GaN (3.0 nm/12 nm) MQW.

For LED A, a 150 nm-thick Mg-doped p-GaN contact layer was grown directly on the MQW without a p-AlGaN EBL. For LED B, a 40 nm thick Mg-doped p-Al0.22Ga0.78N EBL was grown on the MQW, followed by a 110 nm thick Mg-doped p-GaN contact layer. 4

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RESULT AND DISCUSSION

FIG. 1. (Color online) EL spectra with increasing current for (a) LED A without an EBL and (b) LED B with a p-AlGaN EBL.

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(c) the variations of FWHM, and (d) EL peak energies as a function of current.

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FIG. 2. (Color online) (a) Reverse-bias dependent ER spectra and (b) peak energies and intensities of ER spectra with reverse-bias voltages for LED A without an EBL and LED B with a p-AlGaN EBL.

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FIG. 3. (Color online) Time-resolved PL spectra at selected time for (a) LED A without an EBL and (b) LED B with a p-AlGaN EBL.

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CONCLUSION

investigated the effect of a p-AlGaN EBL on the piezoelectric field in InGaN/GaN MQW LEDs. In contrast with the LEDs without a p-AlGaN EBL, the LEDs with a p-AlGaN EBL exhibited reduced blueshift and a sublinear increase of full width at half maximum in their EL spectra at low current densities.

Furthermore, based on the QCSE model, the residual strain is estimated and it is used for our x-ray kinetic simulation. Our simulation considering the strain relaxation agrees well with the measured XRD patterns.

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REFERENCES

Nakamura, Science 281, 956 (1998).E. F. Schubert and J. K. Kim, Science 308, 1274 (2005).T. Mukai, M. Yamada, and S. Nakamura, Jpn. J. Appl. Phys., 38(Part 1), 3976 (1999).E. F. Schubert, Light-Emitting Diodes (Cambridge University Press, Cambridge,2003).5S.-H. Han, D.-Y. Lee, S.-J. Lee, C.-Y. Cho, M.-K. Kwon, S. P. Lee, D. Y.Noh, D.-J. Kim, Y. C. Kim, and S.-J. Park, Appl. Phys. Lett. 94, 231123(2009).M. H. Kim, M. F. Schubert, Q. Dai, J. K. Kim, E. F. Schubert, J. Piprek, and Y. Park, Appl. Phys. Lett. 91, 183507 (2007).Y.-K. Kuo, M.-C. Tsai, and S.-H. Yen, Opt. Commun. 282, 4252 (2009).S.-H. Park and S.-L. Chuang, Appl. Phys. Lett. 72, 3103 (1998).T. M. Hsu, C. Y. Lai, W.-H. Chang, C.-C. Pan, C.-C. Chuo, and J.-I. Chyi, Appl. Phys. Lett. 84, 1114 (2004).F. H. Pollak, “Modulation Spectroscopy of Semiconductors and Semiconductor Microstructures,” in Handbook on Semiconductors, edited by T. S. Moss (Elsevier, Amsterdam, 1994), Vol. 2, pp. 527–635.G. Franssen, P. Perlin, and T. Suski, Phys. Rev. B 69, 045310 (2004).H. S. Kim, J. Y. Lin, H. X. Jiang, W. W. Chow, A. Botchkarev, and H. Morkoc, Appl. Phys. Lett. 73, 3426 (1998).

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Thanks for your attention !

ssl lab. ssl lab. solid state lighting lab. southern taiwan university 1 adviser : hon kuan adviser...

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