Relaxational polarization and charge injection in thin films of silicon nitride

Abstract

Relaxational polarization phenomena and charge injection in silicon nitride deposited on an n-type silicon substrate are studied. After application of low electric fields (< 1 MV cm −1), currents with a time dependence j∼t −α, α ≈ 1 in a time range 500 ns⩽t⩽ 10,000 s flow to the dielectric. After short circuiting, currents with the same time behaviour but opposite sign flow back in the outer circuit. These currents are due to reversible protons fluctuations within the silicon nitride. At higher fields strengths, a charge injection process sets in. About 0·05 s after application of a field E = 3·5 MV cm −1 , the currents deviate from the t −1 law and become constant. This charge injection process depends upon the density of protons within the silicon nitride.