FIG. 4. Electroluminescencespectra of (a) Sample A (withshallow TQW), (b) Sample B(with shallow RQW), (c) Sample C (w/o. shallow QWs) at Various injection currents. (d) The magnitude of the blue-shift and the FWHM of the EL emission peak in the three samples as a function of injection current.

1.8 nm 2.1 nm

5.1 nm

The LED devices with shallow TQW gave a 0.35 V lower

turn-on voltage and an 80% higher lighting efficiency than

those of LEDs without shallow QWs.

The improvements were ascribed to the weakening effect

of the inserted shallow TQW on the polarization field in the

c-plane GaN-LEDs, leading to enhanced lighting efficiency

and reduced efficiency-droop.

Conclusion

(1)E. F. Schubert and J. K. Kim, Science 308, 1274 (2005).

(2)S. Huang, Y. Xian, B. Fan, Z. Zheng, Z. Chen, W. Jia, H. Jiang, and G.Wang, J. Appl. Phys. 110, 064511 (2011).

(3)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).

(4)S. J. Chang, S. C. Wei, Y. K. Su, and W. C. Lai, J. lectrochem. Soc. 154,H871 (2007).

References