Published in J. Electron. Mater. 32, 855 (2003).

Growth of GaN on porous SiC and GaN substrates

C. K. Inoki (a), T. S. Kuan (a), C. D. Lee (b), Ashutosh Sagar (b), R. M. Feenstra (b), D. D. Koleske (c), D. J. Diaz (d), P. W. Bohn (d), and I. Adesida (d)
(a) Department of Physics, University at Albany, SUNY, Albany, NY 12222
(b) Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
(c) Chemical Processing Science Dept., Sandia National Laboratories, Albuquerque, NM 87185
(d) Beckman Institute, University of Illinois, Urbana, IL 61801


We have studied the growth of GaN on porous SiC and GaN substrates, employing both plasma-assisted molecular beam epitaxy (PAMBE) and metalorganic chemical vapor deposition (MOCVD). For growth on porous SiC, transmission electron microscopy (TEM) observations indicate that the epitaxial GaN growth initiates primarily from surface areas between pores, and the exposed surface pores tend to extend into GaN as open tubes and trap Ga droplets. The dislocation density in the GaN layers is similar to, or slightly less than, that observed in layers grown on non-porous substrates. For the case of GaN growth on porous GaN the overgrown layer replicates the underlying dislocation structure (although considerable dislocation reduction can occur as this overgrowth proceeds, independent of the presence of the porous layer). The GaN layers grown on a porous SiC substrate were found to be mechanically more relaxed than those grown on non-porous substrates; electron diffraction patterns indicate that the former are free of misfit strain or are even in tension after cooling to room temperature. Significant changes in the stress of the overgrown layers on porous GaN were also found, as seen in line shifts of low-temperature photoluminescence spectra.

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