The thermal stability of Si/Si1-x-yGexCy/Si quantum wells was studied by high resolution x-ray diffraction, Fourier transform infrared spectroscopy, and defect etching. There are different pathways of strain relaxation in this material system, depending on the annealing temperature. The lattice structure of Si1-x-yGexCy was as stable as the Si1 - xGex alloys at an annealing temperature of 800 °C for 2 h. At an annealing temperature of 900 °C for 2 h. the structures of both Si1 - x - yGexCy and Si1 - xGex started to relax. The addition of C enhanced the Ge outdiffusion in Si1 - x - yGexCy, compared to that of Si1 - xGev. For the annealing temperatures of 950 and 1000 °C for 2 h, the Si1 - xGex continued to relax with the decrease of strain in the quantum wells, but the Si1 - x - yGexCy relaxed with the increase of the strain due to the formation of SiC precipitates. Misfit dislocation formation was observed in the Si1 - x - yGexCy alloys with initial thicknesses below the critical thickness after annealing at 1000 °C for 2 h. This relaxation is probably caused by the SiC precipitation, since SiC precipitates can reduce the strain compensation and, therefore, decrease the critical thickness.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)