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Paramagnetic point defects in amorphous thin films of SiO{sub 2} and Si{sub 3}N{sub 4}: An update

Warren, William L.

Recent research on point defects in thin films of SiO{sub 2} and Si{sub 3}SN{sub 4} on Si is presented and reviewed. In SiO{sub 2} it is now clear that no one type of E{prime} center is the sole source of radiation-induced positive charge; hydrogenous moieties or other types of E{prime} are proposed. Molecular orbital theory and easy passivation of E{prime} by H{sub 2} suggest that released H might depassivate P{sub b} sites. A charged E{prime}{sub {delta}} center has been seen in Cl-free SIMOX and thermal oxide film, and it is reassigned to an electron delocalized over four O{sub 3}{equivalent_to}Si units around a fifth Si. In Si{sub 3}N{sub 4} a new model for the amphoteric charging of Si{equivalent_to}N{sub 3} moieties is based on local shifts in defect energy with respect to the Fermi level, arising from nonuniform composition; it does not assume negative-U electron correlation. A new defect NN{sub 2}{sup 0} has been identified, with dangling orbital on a 2-coordinated N atom bonded to another N.