OXYGEN INCORPORATION AND OXYGEN-INDUCED DEFECT FORMATION IN THIN SI AND SI1-XGEX LAYERS ON SILICON GROWN BY CHEMICAL-VAPOR-DEPOSITION AT ATMOSPHERIC-PRESSURE

The incorporation of oxygen into thin epitaxial Si and heteroepitaxial Si1-xGex layers deposited, applying a conventional atmospheric pressu re process, from silane, germane, hydrogen chloride, and hydrogen gas mixtures in a temperature range from 1070 to 720-degrees-C is analyzed . The role of oxygen for defect formation has been shown by means of a correlation between high resolution defect analysis using transmissio n electron microscopy and quantitative oxygen depth profiling using Au ger electron spectroscopy and secondary ion mass spectrometry. In the low-temperature region traces of residual H2O vapor lead to oxygen pre cipitation. These precipitates are the origin of extended lattice defe cts such as stacking faults and microtwins and can result in highly de fective films with polycrystalline inclusions and increased surface ro ughness. It was found that, in order to prevent the observed defects, it is necessary to keep the oxygen concentration below 3 X 10(19) cm-3 . However, by carefully controlling the experimental parameters it is also possible to realize nearly defect-free structures with high oxyge n concentrations up to 10(20) cm-3.