Thermodynamic behaviour of GeO 2 formed by oxygen implantation into relaxed Si 0.5Ge 0.5 alloy
Abstract
The thermal stability of GeO 2 formed by oxygen implantation into Si 0.5Ge 0.5 alloy has been investigated and quantified. The sample used in this experiment consisted of a 900 nm relaxed layer of Si 0.5Ge 0.5 alloy capped with 78 nm of silicon which was grown on a (100) Si n-type wafer. This was then implanted with a dose of 1.8 × 10 18 O +/cm 2 at 200 keV and specimens from the implanted region were annealed for 1 h at various temperatures. The composition and thickness of the oxide layer, which consisted of SiO 2 + GeO 2, and redistribution of elemental silicon, germanium and oxygen were determined by Rutherford backscattering spectroscopy. The chemical bonding of silicon and germanium to oxygen was determined using X-ray photoelectron spectroscopy. It is found that the germanium was rejected from the oxide layer and segregated at the interface between SiGe/oxide and oxide/SiGe. The driving force for the mass transport can be attributed to the higher chemical potential of germanium in the oxide layer, which is a consequence of the difference in the free energies of formation of SiO 2 and GeO 2.
- Publication:
-
Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- March 1995
- DOI:
- 10.1016/0168-583X(94)00500-1
- Bibcode:
- 1995NIMPB..96..281Z