Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-19T11:13:42.162Z Has data issue: false hasContentIssue false
  • English
  • Français

A Microscopic Evaluation of the Surface Structure of OMVPE Deposited α-GaN Epilayers

Published online by Cambridge University Press:  21 February 2011

G. S. Rohrer ,
J. Payne ,
W. Qian ,
M. Skowronski ,
K. Doverspike ,
L. B. Rowland  and
D. K. Gaskill
G. S. Rohrer
Affiliation:
Carnegie Mellon University, Department of Materials Science and Engineering, Pittsburgh, PA 15213, USA
J. Payne
Affiliation:
Carnegie Mellon University, Department of Materials Science and Engineering, Pittsburgh, PA 15213, USA
W. Qian
Affiliation:
Carnegie Mellon University, Department of Materials Science and Engineering, Pittsburgh, PA 15213, USA
M. Skowronski
Affiliation:
Carnegie Mellon University, Department of Materials Science and Engineering, Pittsburgh, PA 15213, USA
K. Doverspike
Affiliation:
Laboratory for Advanced Material, Synthesis Naval Research Laboratory, Washington, DC 20375, USA
L. B. Rowland
Affiliation:
Laboratory for Advanced Material, Synthesis Naval Research Laboratory, Washington, DC 20375, USA
D. K. Gaskill
Affiliation:
Laboratory for Advanced Material, Synthesis Naval Research Laboratory, Washington, DC 20375, USA
Get access

Abstract

The surface structure of organometallic vapor phase epitaxy (OMVPE) grown α-GaN films was investigated using optical and scanning force microscopy (SFM). Optical microscopy shows that the surface is decorated with several different types of faceted features that have lateral dimensions of 10 to 75 μm and occur with a density of approximately 104/cm2. SFM images show that on the flat regions of the surface, single diatomic layer steps, 2.6 Å high, are straight, evenly spaced (at 500 to 1500 Å intervals), and oriented along á101ñ directions. The SFM images also show that the regular step patterns are often interrupted by faceted growth hillocks, 0.8 to 5 μm in diameter and 120 to 400 Å high, that occur with a density of 106/cm2. An open-core screw dislocation with a Burgers vector of 5.2 Å occurs at the center of each hillock and is a source for spiral steps. Other dislocations are also observed to intersect the flat regions of the surface and create a step, but these have smaller Burgers vectors, do not form spirals, and do not have open cores. Based on these observations, we conclude that thick OMVPE GaN films grow by a combination of the layer-by-layer and spiral growth mechanisms.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 395: Symposium AAA – Gallium Nitride and Related Materials: The First International Symp , 1995 , 381
Copyright
Copyright © Materials Research Society 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1 Morkoç, H., Strite, S., Gao, G. B., Lin, M. F., Sverdlov, B. and Burns, M., J. Appl. Phys. 76, 1363 (1994).Google Scholar
2 Amano, H., Sawaki, N., Akasaki, I. and Toyoda, Y., Appl. Phys. Lett. 48, 353 (1986).Google Scholar
3 Amano, H., Akasaki, I., Hiramatsu, K., Koide, Y., Sawaki, H., Thin Solid Films 163, 415 (1988).Google Scholar
4 Akasaki, I., Amano, H., Koide, Y., Hiramatsu, K., Sawaki, H., J. Crystal Growth 98, 209 (1989).Google Scholar
5 Qian, W., Skowronski, M., Graef, M. D., Doverspike, K., Rowland, L. B. and Gaskill, D. K., Appl. Phys. Lett. 66, 1252 (1995).Google Scholar
6 Doverspike, K., Rowland, L. B., Gaskill, D. K., Binari, S. C. and Freitas, J. J.A., J. Electron. Mater. 24, 269 (1995).Google Scholar
7 Qian, W., Skowronski, M., Doverspike, K., Rowland, L. B. and Gaskill, D. K., J. Crystal Growth 151, 396 (1995).Google Scholar
8 Qian, W., Rohrer, G. S., Skowronski, M., Doverspike, K., Rowland, L. B., and Gaskill, D. K., Applied Physics Letters 67, 2284 (1995).Google Scholar
9 Frank, F. C., Acta Cryst. 4, 497 (1951).Google Scholar