AACG West 17^th Conference on Crystal Growth and Epitaxy, 2000

Effects of Sb Surfactant-Mediated Growth on Dislocations in Si_1-xGe_x

R. L. Forrest, M. S. Goorsky
Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095-1595
J. L. Liu, K. L. Wang,
Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, California 90095-1594

 

The effect of using an Sb surfactant during the growth of Si_1-xGe_x on [001] Si via molecular beam epitaxy (MBE) is investigated. Two samples with 2000 Å Si_0.89Ge_0.11 epilayers were grown with and without an Sb surfactant under otherwise identical conditions, as were several samples of graded buffer layers. The composition profile and relaxation of all of the epitaxial layers were determined from high-resolution x-ray diffraction line scans and reciprocal space maps of the (004) and (224) reflections. These measurements indicate that the box profile epilayer grown without a surfactant was pseudomorphic, as expected, while the box profile epilayer grown with an Sb surfactant was 40% relaxed. The Sb surfactant-mediated growth of Si_1-xGe_x graded buffer layers results in epilayers that are smooth and contain relatively few threading dislocations (1.5 x 10⁴ cm^-2).¹ Based on our results, we propose that the Sb surfactant increases the misfit dislocation glide velocity. This results in greater relaxation and smoother epilayers.

1. Liu, J. L., Moore, C. D., U'Ren, G. D., Luo, Y. H., Lu, Y., Jin, G., Thomas, S. G., Goorsky, M. S., Wang, K. L., App. Phys. Lett. 75, 1586 (1999).