Ammonothermal bulk GaN substrates for LEDs

W. Jiang; D. Ehrentraut; D. S. Kamber; B. C. Downey; J. Cook; M. Grundmann; R. T. Pakalapati; H. Yoo; M. P. D'Evelyn

doi:10.1117/12.2042587

27 February 2014 Ammonothermal bulk GaN substrates for LEDs

W. Jiang, D. Ehrentraut, D. S. Kamber, B. C. Downey, J. Cook, M. Grundmann, R. T. Pakalapati, H. Yoo, M. P. D'Evelyn

Proceedings Volume 9003, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVIII; 900313 (2014) https://doi.org/10.1117/12.2042587
Event: SPIE OPTO, 2014, San Francisco, California, United States

Abstract

Soraa has developed a novel ammonothermal approach for growth of high quality, true bulk GaN crystals at a greatly reduced cost. Soraa’s patented approach, known as SCoRA (Scalable Compact Rapid Ammonothermal) utilizes internal heating to circumvent the material-property limitations of conventional ammonothermal reactors. The SCoRA reactor has capability for temperatures and pressures greater than 650 °C and 500 MPa, respectively, enabling higher growth rates than conventional ammonothermal techniques, yet is less expensive and more scalable than conventional autoclaves fabricated from nickel-based superalloys. SCoRA GaN growth has been performed on c-plane and m-plane seed crystals with diameters between 5 mm and 2" to thicknesses of 0.5-4 mm. The highest growth rates are greater than 40 μm/h and rates in the 10-30 μm/h range are routinely observed. These values are significantly larger than those achieved by conventional ammonothermal GaN growth and are sufficient for a cost-effective manufacturing process. Two-inch diameter, crack-free, free-standing, n-type bulk GaN crystals have been grown. The crystals have been characterized by a range of techniques, including x-ray diffraction rocking-curve (XRC) analysis, optical microscopy, cathodoluminescence (CL), optical spectroscopy, and capacitance-voltage measurements. The crystallinity of the grown crystals is very good, with FWHM values of 15-80 arc-sec and average dislocation densities below 5 x 10⁵ cm^-2.

Citation Download Citation

W. Jiang, D. Ehrentraut, D. S. Kamber, B. C. Downey, J. Cook, M. Grundmann, R. T. Pakalapati, H. Yoo, and M. P. D'Evelyn "Ammonothermal bulk GaN substrates for LEDs", Proc. SPIE 9003, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XVIII, 900313 (27 February 2014); https://doi.org/10.1117/12.2042587

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