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 via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
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).
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).
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).
Schmidt, M. C. et al. Demonstration of nonpolar m-plane InGaN/GaN laser diodes. Jpn. J. Appl. Phys. 46, L190–L191 (2007).
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).
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).
Porowski, S. Near defect free GaN substrates. MRS Internet J. Nitride Semicond. Res. 4S1, G1.3 (1999).
Inoue, T. et al. Pressure-controlled solution growth of bulk GaN crystals under high pressure. Phys. Status Solidi B 223, 15–27 (2001).
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).
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).
Peters, D. Ammonothermal synthesis of aluminum nitride. J. Cryst. Crowth 104, 411–418 (1990).
Dwilinski, R. et al. AMMONO method of BN, AlN and GaN synthesis and crystal growth. MRS Internet J. Nitride Semicond. Res. 3, 25 (1998).
Ketchum, D. R. & Kolis, J. W. Crystal growth of gallium nitride in supercritical ammonia. J. Cryst. Growth 222, 431–434 (2001).
Purdy, A. P., Jouet, R. J. & George, C. F. Ammonothermal recrystallization of gallium nitride with acidic mineralizers. Cryst. Growth Design 2, 141–145 (2002).
Hashimoto, T. et al. Growth of gallium nitride via fluid transport in supercritical ammonia. J. Cryst. Growth 275, e525–e530 (2005).
Kagamitani, Y. et al. Ammonothermal epitaxy of thick GaN film using NH4Cl mineralizer. Jpn. J. Appl. Phys. 45, 4018–4020 (2006).
Hashimoto, T. et al. Phase selection of microcrystalline GaN synthesized in supercritical ammonia. J. Cryst. Growth 291, 100–106 (2006).
Dwilinski, R. T. et al. Bulk monocrystalline gallium nitride. United States patent 6,656,615 B2 (2003).
Callahan, M. et al. GaN single crystals grown on HVPE seeds in alkaline supercritical ammonia. J. Mater. Sci. 41, 1399–1407 (2006).
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).
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).
Morkoc, H. Comprehensive characterization of hydride VPE grown GaN layers and templates. Mater. Sci. Eng. R33, 135–207 (2001).
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).
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).
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
Authors and Affiliations
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
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Rights 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
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nmat1955
This article is cited by
-
Fabrication of gallium nitride and nitrogen doped single layer graphene hybrid heterostructures for high performance photodetectors
Scientific Reports (2020)
-
Investigations on structural and spectral properties of undoped and Mn2+ doped SrZn2(PO4)2 nanophosphors for light emitting devices
Journal of Materials Science: Materials in Electronics (2019)
-
Synthesis and Luminescence Properties of CaGd2(MoO4)4:Dy3+, Eu3+, Tm3+ Phosphors for Warm White UV LEDs
Journal of Electronic Materials (2018)
-
Pathway Towards High-Efficiency Eu-doped GaN Light-Emitting Diodes
Scientific Reports (2017)
-
The investigation of stress in freestanding GaN crystals grown from Si substrates by HVPE
Scientific Reports (2017)