Relaxed Si1−xGex/Si1−x−yGexCy buffer structures with low threading dislocation density
- 26 May 1997
- journal article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 70 (21) , 2813-2815
- https://doi.org/10.1063/1.119067
Abstract
We demonstrate the growth of a relaxed, only 1 μm thick, stepwise graded buffer based on a combination of Si1−xGex and Si1−x−yGexCy. This buffer concept relies on the retardation of dislocation glide in Si1−x−yGexCy relative to strain equivalent Si1−xGex on silicon. The homogeneous Si1−xGex layer with x=30% on top of the buffer structure is (73±5)% relaxed. For the nonoptimized buffer growth, we already find a threading dislocation density below 105 cm−2. A stepped Si1−xGex buffer with the identical thickness and strain profile grown with the same temperature ramp yields a threading dislocation density above 107 cm−2. This indicates that the addition of carbon is a promising way for new relaxed buffer concepts with low threading dislocation densities.Keywords
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