APPLIED PHYSICS LETTERS 96, 051113 , 2010 Effect of Mg doping in the barrier of InGaN/GaN multiple quantum well on optical power of light-emitting diodes Sang-Heon Han, Chu-Young Cho, Sang-Jun Lee, Tae-Young Park, Tae-Hun Kim, Seung Hyun Park, Sang Won Kang, Je Won Kim, Yong Chun Kim, and Seong-Ju Park APPLIED PHYSICS LETTERS 96, 051113 , 2010 J.K. Lee

Outline Introduction Experiment Results and discussion Conclusion

Introduction Mg doping in the barriers of MQW enhances photoluminescence intensity, thermal stability, and internal quantum efficiency of LED. The improvement in output power is attributed to the enhanced hole injection to well layers in MQW with Mg-doped barriers.

Mg-doped GaN concentration  4.94*1016/cm3 Experiment P Ti/Al 3nm InGaN Well 750℃ 8nm GaN Barrier 800℃ A ITO P-GaN 200 nm P-AlGaN 20 nm N Ti/Au MQW 5 period u-GaN / Mg-doped GaN / u-GaN B 2 nm / 4 nm / 2 nm N-GaN 2μm buffer u-GaN concentration  5.02*1018/cm3 Sapphire Mg-doped GaN concentration  4.94*1016/cm3 Chip Size ： 300*300 μm2

Experiment Mg doped GaN Un doped GaN Un doped GaN N-GaN P-AlGaN

Results and discussion FIG. 1. (Color online) (a) Room temperature PL spectra of LED A and LED B (inset: high resolution x-ray diffraction -2 scans for the GaN 0002 reflection of LED A and LED B).

Results and discussion 25% 15% 63% FIG. 1. (b) PL spectra of LED A before and after RTA, (c) PL spectra of LED B before and after RTA.

Results and discussion FIG. 2. Color online Integrated PL intensities as a function of 1/T for LED A and LED B.

Results and discussion 3.8*108/cm2 2.96*108/cm2 9.62 Å 6.98 Å 22% FIG. 3. Color online AFM images of surface morphologies of a LED A and b LED B.

Results and discussion 3.54V 3.63V FIG. 4. Color online a I-V curve of LED A and LED B, b light output power of LED A and LED B as a function of current.

Results and discussion FIG. 5. Color online Energy band diagrams of well and barrier layer of LED A and LED B at 4 V, a valence band and b conduction band. Carrier concentration throughout MQW at 4 V, c LED A and d LED B.

Conclusion We investigated the effect of Mg doping in the barrier layers of MQW of InGaN/GaN LED. PL measurements showed that thermal stability was improved and IQE was increased for LED with Mg-doped MQW barriers. The reduced defect density and RMS roughness of MQWs were also confirmed by AFM images.

Influence of Mg Doping on the Morphological, Optical, and Structural Properties of InGaN/GaN Multiple Quantum Wells Z. CHEN, N. FICHTENBAUM, D. BROWN, S. KELLER, U.K. MISHRA, S.P. DENBAARS, and S. NAKAMURA Journal of ELECTRONIC MATERIALS, Vol. 37, No. 5, 2008

Outline Introduction Experiment Results and discussion Conclusion References

Introduction The V-defect density was observed to decrease with increasing magnesium doping concentration from 109 cm-2 (no doping) to 106 cm-2 (Cp2Mg: 0.04 sccm) and further to 0 (Cp2 Mg: 0.2 sccm). These results suggest that magnesium doping in MQWs might improve the optical properties of GaN photonic devices.

Experiment Barrier  3 nm Well  10 nm Ti/Al ITO P-GaN 200 nm P-AlGaN 20 nm Barrier  3 nm Well  10 nm N Ti/Au MQW 5 period N-GaN 2μm Buffer 25nm Cp2Mg doping precursor flow was from 0 sccm to 0.04 sccm and 0.2sccm. Sapphire Chip Size ： 300*300 μm2

Results and discussion 1*109/cm-2 4*106/cm-2 0 sccm 0.04 sccm 0.2 sccm Fig. 1. 5 lm * 5 lm AFM images of InGaN/GaN MQW at different Mg doping levels: (a) 0 sccm, (b) 0.04 sccm, and (c) 0.2 sccm. The height scale is 10 nm for all samples.

Results and discussion 0 sccm 0.04 sccm 0.2 sccm Fig. 2. 1 lm * 1 lm AFM images of InGaN/GaN MQW at different Mg doping levels: (a) 0 sccm, (b) 0.04 sccm, and (c) 0.2 sccm. The height scale is 10 nm for all samples.

Results and discussion Fig. 3. PL spectra of InGaN/GaN MQW at different Mg doping levels.

Conclusion The AFM measurements indicated that Mg doping improved the surface morphology of the MQWs and enhanced twodimensional growth. The density of the V-defects was observed to decrease from 109 cm-2 (undoped) to 106 cm-2 and further to zero with increasing Mg doping concentration.

References Sang-Heon Han, Chu-Young Cho, Sang-Jun Lee, Tae-Young Park, Tae-Hun Kim, Seung Hyun Park, Sang Won Kang, Je Won Kim, Yong Chun Kim, and Seong-Ju Park ,” Effect of Mg doping in the barrier of InGaN/GaN multiple quantum well on optical power of light-emitting diodes ” , APPLIED PHYSICS LETTERS 96, 051113 , 2010. Z. Chen, N. Fichtenbaum, D. Brown, S. Keller, U.K. Mishra, S.P. Denbaars, and S. Nakamura ,” Influence of Mg Doping on the Morphological, Optical, and Structural Properties of InGaN/GaN Multiple Quantum Wells ” , Journal of ELECTRONIC MATERIALS, Vol. 37, No. 5, 2008.