Published in Mat. Res. Soc. Symp. Proc. Vol. 722, K1.3.1 (2002).
Growth of GaN on porous SiC substrates by plasma-assisted molecular beam epitaxy
C. K. Inoki (a), T. S. Kuan (a), C. D. Lee (b), Ashutosh Sagar (b), and R. M. Feenstra (b)
(a)Department of Physics, University at Albany, SUNY, Albany, NY 12222
(b)Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
Abstract
We have explored the growth of GaN on porous SiC substrates by
plasma-assisted molecular beam epitaxy. The porous 4H- and
6H-SiC(0001) substrates used in this study contain 10 to 100-nm sized
pores and a thin skin layer at the surface. This skin layer was
partially removed prior to the growth by H-etching. Transmission
electron microscopy (TEM) observations indicate that the epitaxial GaN
growth initiates from the surface areas between pores, and the exposed
surface pores tend to extend into GaN as open tubes and trap Ga
droplets. Plan-view TEM observations indicate that the GaN layers
grown on porous substrates contain fewer dislocations than layers
grown on non-porous substrates by roughly a factor of two. The GaN
layers grown on a porous SiC substrate were also 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.
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