Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A GaN bulk crystal with improved structural quality grown by the ammonothermal method

Nature Materials volume 6, pages 568–571 (2007)Cite this article

Abstract

The realization of high-performance optoelectronic devices, based on GaN and other nitride semiconductors, requires the existence of a high-quality substrate. Non-polar or semipolar substrates have recently been proven to provide superior optical devices to those on conventional c-plane substrates1,2,3,4. Bulk GaN growth enables GaN substrates sliced along various favourable crystal orientations. Ammonothermal growth is an attractive method for bulk GaN growth owing to its potential to grow GaN ingots at low cost. Here we report on improvement in the structural quality of GaN grown by the ammonothermal method. The threading dislocation densities estimated by plan-view transmission electron microscopy observations were less than 1×106 cm−2 for the Ga face and 1×107 cm−2 for the N face. No dislocation generation at the interface was observed on the Ga face, although a few defects were generated at the interface on the N face. The improvement in the structural quality, together with the previous report on growth rate5 and scalability6, demonstrates the commercial feasibility of the ammonothermal GaN growth.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

Buy

All prices are NET prices.

Figure 1: Cross-sectional scanning electron micrograph of GaN grown for 50 days.
Figure 2: Cross-sectional TEM images of the GaN crystal grown by the ammonothermal method.
Figure 3: Nomarski microscope images for the grown surface after H3PO4 etching at 160 ∘C.

References

  1. Schmidt, M. C. et al. High power and high external efficiency m-plane InGaN light emitting diodes. Jpn. J. Appl. Phys. 46, L126–L128 (2007).

    CAS  Article  Google Scholar 

  2. Tyagi, A. et al. High brightness violet InGaN/GaN light emitting diodes on semipolar bulk GaN substrates. Jpn. J. Appl. Phys. 46, L129–L131 (2007).

    CAS  Article  Google Scholar 

  3. Okamoto, K., Ohta, H., Chichibu, S. F., Ichihara, J. & Takasu, H. Continuous-wave operation of m-plane InGaN multiple quantum well laser diodes. Jpn. J. Appl. Phys. 46, L187–L189 (2007).

    CAS  Article  Google Scholar 

  4. Schmidt, M. C. et al. Demonstration of nonpolar m-plane InGaN/GaN laser diodes. Jpn. J. Appl. Phys. 46, L190–L191 (2007).

    CAS  Article  Google Scholar 

  5. Callahan, M. J. et al. Growth of GaN crystals under ammonothermal conditions. Mater. Res. Soc. Symp. Proc. 798, Y2.10.1–Y2.10.6 (2004).

    Google Scholar 

  6. Hashimoto, T., Fujito, K., Saito, M., Speck, J. S. & Nakamura, S. Ammonothermal growth of GaN on an over-1-inch seed crystal. Jpn. J. Appl. Phys. 44, L1570–L1572 (2005).

    CAS  Article  Google Scholar 

  7. Porowski, S. Near defect free GaN substrates. MRS Internet J. Nitride Semicond. Res. 4S1, G1.3 (1999).

    Google Scholar 

  8. Inoue, T. et al. Pressure-controlled solution growth of bulk GaN crystals under high pressure. Phys. Status Solidi B 223, 15–27 (2001).

    CAS  Article  Google Scholar 

  9. Yamane, H., Shimada, M., Sekiguchi, T. & DiSalvo, F. J. Morphology and characterization of GaN single crystals grown in a Na flux. J. Cryst. Growth 186, 8–12 (1998).

    CAS  Article  Google Scholar 

  10. Kawamura, F. et al. Novel liquid phase epitaxy (LPE) growth method for growing large GaN single crystals: introduction of the flux film coated-liquid phase epitaxy (FFC-LPE) method. Jpn. J. Appl. Phys. 42, L879–L881 (2003).

    CAS  Article  Google Scholar 

  11. Peters, D. Ammonothermal synthesis of aluminum nitride. J. Cryst. Crowth 104, 411–418 (1990).

    CAS  Article  Google Scholar 

  12. Dwilinski, R. et al. AMMONO method of BN, AlN and GaN synthesis and crystal growth. MRS Internet J. Nitride Semicond. Res. 3, 25 (1998).

    Article  Google Scholar 

  13. Ketchum, D. R. & Kolis, J. W. Crystal growth of gallium nitride in supercritical ammonia. J. Cryst. Growth 222, 431–434 (2001).

    CAS  Article  Google Scholar 

  14. Purdy, A. P., Jouet, R. J. & George, C. F. Ammonothermal recrystallization of gallium nitride with acidic mineralizers. Cryst. Growth Design 2, 141–145 (2002).

    CAS  Article  Google Scholar 

  15. Hashimoto, T. et al. Growth of gallium nitride via fluid transport in supercritical ammonia. J. Cryst. Growth 275, e525–e530 (2005).

    CAS  Article  Google Scholar 

  16. Kagamitani, Y. et al. Ammonothermal epitaxy of thick GaN film using NH4Cl mineralizer. Jpn. J. Appl. Phys. 45, 4018–4020 (2006).

    CAS  Article  Google Scholar 

  17. Hashimoto, T. et al. Phase selection of microcrystalline GaN synthesized in supercritical ammonia. J. Cryst. Growth 291, 100–106 (2006).

    CAS  Article  Google Scholar 

  18. Dwilinski, R. T. et al. Bulk monocrystalline gallium nitride. United States patent 6,656,615 B2 (2003).

  19. Callahan, M. et al. GaN single crystals grown on HVPE seeds in alkaline supercritical ammonia. J. Mater. Sci. 41, 1399–1407 (2006).

    CAS  Article  Google Scholar 

  20. Hashimoto, T. et al. Structural characterization of thick GaN films grown on free-standing GaN seeds by the ammonothermal method using basic ammonia. Jpn. J. Appl. Phys. 44, L797–L799 (2005).

    CAS  Article  Google Scholar 

  21. Reiher, A., Blasing, J., Dadgar, A. & Krost, A. Depth-resolving structural analysis of GaN layers by skew angle x-ray diffraction. Appl. Phys. Lett. 84, 3537–3539 (2004).

    CAS  Article  Google Scholar 

  22. Morkoc, H. Comprehensive characterization of hydride VPE grown GaN layers and templates. Mater. Sci. Eng. R33, 135–207 (2001).

    CAS  Article  Google Scholar 

  23. Hashimoto, T. et al. Ammonothermal growth of GaN utilizing negative temperature dependence of solubility in basic ammonia. Mater. Res. Soc. Symp. Proc. 831, E2.8.1–E2.8.6 (2005).

    Google Scholar 

  24. Hong, S. K., Yao, T., Kim, B. J., Yoon, S. Y. & Kim, T. I. Origin of hexagonal-shaped etch pits formed in (0001) GaN films. Appl. Phys. Lett. 77, 82–84 (2000).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

The authors acknowledge F. Orito, K. Fujito and M. Saito at Mitsubishi Chemical Corporation for supplying HVPE-grown free-standing GaN substrates.

Author information

Author notes

  1. Materials Department, University of California, Santa Barbara, California 93106-5050, USA

  2. ERATO/JST UCSB group, University of California, Santa Barbara, California 93106-5050, USA

Affiliations

  1. Tadao Hashimoto

Authors
  1. Tadao Hashimoto
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Feng Wu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. James S. Speck
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Shuji Nakamura
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

F.W. carried out the TEM characterization. J.S.S. and F.W. provided interpretation of structural characterization and fruitful discussions. S.N. directed the research.

Corresponding author

Correspondence to Tadao Hashimoto.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Hashimoto, T., Wu, F., Speck, J. et al. A GaN bulk crystal with improved structural quality grown by the ammonothermal method. Nature Mater 6, 568–571 (2007). https://doi.org/10.1038/nmat1955

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1955

Further reading

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing