Direct assessment of relaxation and defect propagation in different as-grown and in situ post-growth annealed thin Ge/Si and step-graded Si1−xGex/Si buffer layers

Autor: O. Nur, M.Y.A. Yousif, C.J. Patel, Magnus Willander, Daniel Bensahel, R.N Kyutt, Caroline Hernandez, Yves Campidelli
Rok vydání: 2001
Předmět:
Zdroj: Solid-State Electronics. 45:1869-1874
ISSN: 0038-1101
DOI: 10.1016/s0038-1101(01)00225-8
Popis: The strain-sensitive X-ray two-dimensional reciprocal space mapping diffractrometry (2D-RSM) is employed to investigate the relaxation parameters and defect propagation in various thin relaxed buffer layers (RBLs) having a pure Ge top. In addition, we also studied the effect of in situ post-growth thermal treatments at an early growth stage of RBLs with low and intermediate Ge fraction. Both direct Ge epitaxy and multi-layer step-graded epitaxy have been adopted to grow these RBLs using chemical vapor deposition (CVD) at elevated partial pressure (around 10 Torr), which implies a much higher growth rate than RBLs grown using ultra-high vacuum CVD technique. Fully relaxed Ge top layers were obtained for both the direct Ge epitaxy, as well as for the step-graded technique. The results, when comparing these two techniques, favor the direct Ge epitaxy. However, the results of in situ post-growth annealing of the step-graded RBLs indicate a large reduction in the threading dislocations present in the grading regions without a change of relaxation degree or Ge% incorporation in that region.
Databáze: OpenAIRE
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