[1] Z. Chen, G. Bosman, and R. Ochoa, Appl. Phys. Lett. 62, 708 (1993).

[2] P. Steiner, F. Kozlowski, and W. Lang, Appl. Phys. Lett. 62, 2700 (1993).

[3] S. Lazarouk, P. Jaguiro, S. Katsouba, G. Masini, S. La Monica, G. Maiello, and A. Ferrari, Appl. Phys. Lett. 68, 1646 (1996).

[4] P. Hlinomaz, O. Klíma, A. Hospodková, E. Hulicius, J. Oswald, E. Sípek, and J. Koika, Appl. Phys. Lett. 64, 3118 (1994).

[5] H. Shinoda, T. Nakajima, K. Ueno, and N. Koshida, Nature 400, 853 (1999).

[6] K. Ueno and N. Koshida, Appl. Phys. Lett. 74, 93 (1999).

[7] W. H. Zheng, P. Reece, B. Q. Sun, and M. Gal, Appl. Phys. Lett. 84, 3519 (2004).

[8] Z. Gaburro, C. J. Oton, L. Pavesi, and L. Pancheri, Appl. Phys. Lett. 84, 4388 (2004).

[9] L. T. Canham, Appl. Phys. Lett. 57, 1046 (1990).

[10] G. Fu, L. Chu, Y. Zhou, C. Yan, D. Wu, Y. Wang, and Y. Peng, Chinese J. Lasers (in Chinese) 32, 1254 (2005).

[11] L. Chu, L. Lu, Y. Wang, and G. Fu, Chinese J. Lasers (in Chinese) 34, 555 (2007).

[12] J. Wang, H. Guo, L. Li, and P. Lü, Chinese J. Lasers(in Chinese) 34, 1498 (2007).

[13] G. Qin, J. Infrared Millim. Waves (in Chinese) 24, 165 (2005).

[14] Z. Cen, J. Xu, X. Li, W. Li, S. Chen, Y. Liu, X. Huang, and K. Chen, Chin. J. Semicond. (in Chinese) 27, 1016 (2006).

[15] H. Guo, L. Yang, and Q. Wang, Chin. J. Semicond. (in Chinese) 28, 640 (2007).

[16] K. Wang and J. Tang, Semicond. Optoelectron. (in Chinese) 15, 340 (1994).