ABSTRACTThe spatial and energetic characteristics of rf and dc parallel-plate deposition discharges are discussed, along with their implications to plasma chemistry. We discuss the results and interpretation of our recent measurements of silane, disilane, germane, and mixed-gas stochiometry. These yield the initial dissociation branching between even and odd dangling-bond radicals, as well as the relative roles of higher silanes and silyl germanes (produced by the discharge) in the chemistry. Our deposition model and supporting data are discussed, as are various causes of film-quality variations which this suggests.