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Recent Performance of Nonpolar/Semipolar/Polar GaN-based Blue LEDs/LDs and Bulk GaN Crystal Growth

Shuji Nakamura 1S. P. DenBaars 1James S. Speck 1M. C. Schmidt 1K- C. Kim 1R. M. Farrell 1D. F. Feezell 1D. A. Cohen 1M. Saito 1H. Sato 1H. Asamizu 1A. Tyagi 1H. Zhong 1H. Masui 1N. N. Fellows 1M. Iza 1T. Hashimoto 1K. Fujito 2

1. ERATO, JST, UCSB group, Materials Department, Santa Barbara, CA 93106, United States
2. Mitsubishii Chemical Corp., Ibaraki 300-1295, Japan


Charge separation due to spontaneous and piezoelectric polarization inherent to the wurtzite structure has deleterious effects on the performance of most c-axis oriented devices.1) To overcome this problem, Nonpolar GaN, such as a-plain and m-plain GaN or Semipolar GaN substrates have been grown.
We reported the fabrication of violet InGaN/GaN Light Emitting Diodes (LEDs) on semipolar (1011) GaN bulk substrates. The output power and External Quantum Efficiency (EQE) at a driving current of 20 mA were 28 mW and 45 % respectively, with peak electroluminescence (EL) emission wavelength at 411 nm. The LEDs showed minimal shift in peak EL wavelength with increasing drive current indicating an absence of polarization induced electric fields.2) Also, high power and high efficiency nonpolar m-plane nitride LEDs were fabricated on low extended defect bulk m-plane GaN substrates.3) The first nonpolar m-plane (1100) nitride laser diodes (LDs) were realized on low extended defect bulk m-plane GaN substrates.4) Broad area lasers without AlGaN cladding layers were fabricated and tested under pulsed conditions. These laser diodes had threshold current densities (Jth) as low as 3.7-2.3 kA/cm2.5) Stimulated emission was observed around 400 nm. The recent performance of Nonpolar, Semipolar and Polar (c-plain) GaN-based devices are described. Also, I like to talk about the latest result of a GaN bulk crystal growth by anmmothermal method at UCSB.


1. S. Chichibu, T. Azuhata, T. Sota, and S. Nakamura, Appl. Phys. Lett. 69, 4188 (1996)
2.A. Tyagi, H. Zhong, N. N. Fellows, M. Iza, J. S. Speck, S. P. DenBaars, and S.i Nakamura, Jpn. J. Appl. Phys. 46 (2007) L129
3.M. C. Schmidt, K-C Kim, H. Sato, N. Fellows, H. Masui, S. Nakamura, S. P. DenBaars, and J. S. Speck, Jpn. J. Appl. Phys. 46 (2007) L126
4.M.C. Schmidt, K-C Kim, R.M. Farrell, D. F. Feezell, D.l A. Cohen, M. Saito, K.Fujito, J. S. Speck, S.P. DenBaars, and S. Nakamura, Jpn. J. Appl. Phys. L190-L191, Vol 46 (2007).
5.D.F. Feezell, M.C. Schmidt, R. M. Farrell, K-CKim, M. Saito, K. Fujito, D.l A. Cohen, J. S. Speck, S.P. DenBaars, and S. Nakamura, Jpn. J. Appl. Phys. L284-L286, Vol 46 (2007).


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Presentation: Plenary talk at E-MRS Fall Meeting 2007, Plenary session, by Shuji Nakamura
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-06-25 12:01
Revised:   2007-06-25 12:33