This article was presented as part of Symposium W, "Gallium Nitride and Related Alloys" at the 1999 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 28-December 3

Abstract

A new process route for lateral growth of nearly defect free GaN structures via Pendeo-epitaxy is discussed. Lateral growth of GaN films suspended from {110} side walls of [0001] oriented GaN columns into and over adjacent etched wells has been achieved via MOVPE technique without the use of, or contact with, a supporting mask or substrate. Pendeo-epitaxy is proposed as the descriptive term for this growth technique. Selective growth was achieved using process parameters that promote lateral growth of the {110} planes of GaN and disallow nucleation of this phase on the exposed SiC substrate. Thus, the selectivity is provided by tailoring the shape of the underlying GaN layer itself consisting of a sequence of alternating trenches and columns, instead of selective growth through openings in SiO 2 or SiN x mask, as in the conventional lateral epitaxial overgrowth (LEO). Two modes of initiation of the pendeo-epitaxial GaN growth via MOVPE were observed: Mode A - promoting the lateral growth of the {110} side facets into the wells faster than the vertical growth of the (0001) top facets; and Mode B - enabling the top (0001) faces to grow initially faster followed by the pendeo-epitaxial growth over the wells from the newly formed {110} side facets. Four-to-five order decrease in the dislocation density was observed via transmission electron microscopy (TEM) in the pendeo-epitaxial GaN relative to that in the GaN columns. TEM observations revealed that in pendeo-epitaxial GaN films the dislocations do not propagate laterally from the GaN columns when the structure grows laterally from the sidewalls into and over the trenches. Scanning electron microscopy (SEM) studies revealed that the coalesced regions are either defect-free or sometimes exhibit voids. Above these voids the PE-GaN layer is usually defect free.

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References Citing this Article

[1] J.D. Brown, Zhonghai Yu, J. Matthews, S. Harney, J. Boney, J.F. Schetzina, J.D. Benson, K.W. Dang, C. Terrill, Thomas Nohava, Wei Yang, Subash Krishnankutty, MRS Internet J. Nitride Semicond. Res. 4, 9 (1999).

[2] M. Callahan, M. Harris, M. Suscavage, D. Bliss, J. Bailey, MRS Internet J. Nitride Semicond. Res. 4, 10 (1999).

[3] Robert F. Davis, T. Gehrke, K.J. Linthicum, P. Rajagopal, A.M. Roskowski, T. Zheleva, Edward A. Preble, C.A. Zorman, M. Mehregany, U. Schwarz, J. Schuck, R. Grober, MRS Internet J. Nitride Semicond. Res. 6, 14 (2001).

Cite this article as: MRS Internet J. Nitride Semicond. Res. 4S1, G3.38 (2000).

last updated Saturday, November 24, 2001 6:41:08 PM.
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