High Quality, Low Cost Ammonothermal Bulk GaN Substrates

• Published in: Japanese Journal of Applied Physics 2013-08, Vol.52 (8), p.08JA01-08JA01-4
• Main Authors: Ehrentraut, Dirk, Pakalapati, Rajeev T, Kamber, Derrick S, Jiang, Wenkan, Pocius, Douglas W, Downey, Bradley C, McLaurin, Melvin, D'Evelyn, Mark P
• Format: Article
• Language: English
• Subjects: Crystallinity; Crystals; Diffraction; Dislocation density; ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Epitaxial growth; Gallium nitride (GaN), bulk substrate, ammonothermal; Gallium nitrides; Indium gallium nitrides; MATERIALS SCIENCE; Scanning electron microscopy; Seeds
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.52.08JA01

Ammonothermal GaN growth using a novel apparatus has been performed on $c$-plane, $m$-plane, and semipolar seed crystals with diameters between 5 mm and 2 in. to thicknesses of 0.5--3 mm. The highest growth rates are greater than 40 μm/h and rates in the 10--30 μm/h range are routinely observed for all orientations. These values are $5{\mbox{--}}100\times$ larger than those achieved by conventional ammonothermal GaN growth. The crystals have been characterized by X-ray diffraction rocking-curve (XRC) analysis, optical and scanning electron microscopy (SEM), cathodoluminescence (CL), optical spectroscopy, and capacitance--voltage measurements. The crystallinity of the grown crystals is similar to or better than that of the seed crystals, with FWHM values of about 20--100 arcsec and dislocation densities of $1 \times 10^{5}$--$5 \times 10^{6}$ cm -2 . Dislocation densities below $10^{4}$ cm -2 are observed in laterally-grown crystals. Epitaxial InGaN quantum well structures have been successfully grown on ammonothermal wafers.