A Quantitative Study of the Relationship Between Interfacial Carbon and Line Dislocation Density in Silicon Molecular Beam Epitaxy

Silicon layers grown by molecular beam epitaxy on (100) silicon substrates were depth-profiled for carbon and oxygen by secondary ion mass spectrometry (SIMS). The same epitaxial l yers were subjected to a defect etch to reveal dislocation density. A strong correlation isfound between the carbon concentration at the substrate-epitaxy interface and the line dislo-cation density of the epitaxial layer. Layers with interfacial carbon concentration ~ 1021cm-3 exhibit line dislocation densi-ties/> 1OTcm-~, while layers with interfacial carbon concentration ~< 1019cm-3 ( ~<0.01 monolayer carbon) have line dislocation densities ~< 104cm-2. In contrast, no correlation is found between interracial oxygen (as revealed by SIMS) and the line dislo-cation density of the epitaxial layers. It is known that carbon contamination at the sub-strate-epitaxy interface is an influential parameter in the growth of silicon molecular beam epitaxy (MBE) (1-3). For examp~le, Joyce et at. (2) have reported that carbon coverage of approximately 0.01 mono-layer at the silicon substrate is sufficient to cause three-dimensional growth from nuclei rather than th