Published in Phys. Stat. Sol. (a) 200, 44 (2003).
Growth of GaN on porous SiC and GaN substrates
C. K. Inoki(a), T. S. Kuan(a), Ashutosh Sagar(b), C. D. Lee(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 Department, Sandia National Laboratories,
Albuquerque, NM 87185
(d) Beckman Institute, University of Illinois, Urbana, IL 61801
Abstract
GaN films were grown on porous SiC and GaN templates using both
plasma- assisted molecular beam epitaxy (PAMBE) and metal-organic
chemical vapor deposition (MOCVD) to evaluate possible advantage of
epitaxy on a porous substrate. For the growth of GaN on porous SiC by
PAMBE, transmission electron microscopy (TEM) observations indicate
that the exposed SiC suface pores tend to extend into the GaN film as
open tubes and to trap Ga droplets. The GaN layers grown on porous
templates have fewer threading dislocations originating at the
interface, but they have additional defects in the form of half- loop
dislocations which act to relieve the strain in the films. For PAMBE
of GaN on porous GaN, dislocations existing in the porous seed layer
are seen to propagate through the porous layer into the overgrown GaN,
resulting in no dislocation reduction. For MOCVD of GaN on porous
GaN, the initial regrowth tend to bend laterally the dislocations and
enhance their annihilation, resulting in 5-10x fewer dislocations
in the overgrown film.
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