V. Ramachandran, C. D. Lee, and R. M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
A. R. Smith
Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701
J. E. Northrup
Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304
D. W. Greve
Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
Published in J. Cryst. Growth 209, 355 (2000).