OBSERVATION OF MULTIPLE DEFECT STATES AT SILICON SILICON-NITRIDE INTERFACES FABRICATED BY LOW-FREQUENCY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

Silicon nitride films are deposited onto monocrystalline p- and n-type silicon wafers by low-frequency plasma-enhanced chemical vapor deposi tion. Using small-pulse deep-level transient spectroscopy, three diffe rent types of defects are identified at the silicon-silicon nitride in terface. All defects are located in the lower half of the silicon band gap and show a very broad Gaussian-like distribution of the state den sity. For all three defects, the capture cross sections for electrons, sigma(n), and holes, sigma(p), decrease strongly towards the conducti on and valence band edge, respectively, while the capture cross-sectio n ratio sigma(n)/sigma(p) at midgap, and hence the resulting recombina tion rate, is very different for each defect type. (C) 1997 American I nstitute of Physics.