Observation of multiple defect states at silicon–silicon nitride interfaces fabricated by low-frequency plasma-enhanced chemical vapor deposition

Abstract

Silicon nitride films are deposited onto monocrystalline p- and n-type silicon wafers by low-frequency plasma-enhanced chemical vapor deposition. Using small-pulse deep-level transient spectroscopy, three different types of defects are identified at the silicon–silicon nitride interface. All defects are located in the lower half of the silicon band gap and show a very broad Gaussian-like distribution of the state density. For all three defects, the capture cross sections for electrons, σn, and holes, σp, decrease strongly towards the conduction and valence band edge, respectively, while the capture cross-section ratio σn/σp at midgap, and hence the resulting recombination rate, is very different for each defect type.