ELECTRICAL CONDUCTION IN EVAPORATED SILICON OXIDE FILMS

Electrical properties of evaporated silicon oxide films were measured by direct current and thermally stimulated current (T.S.C.) peaks. D.c. measurements in the temperature range 4.2-420 °K and covering a wide range of electric fields give four regions of conduction: mainly ionic ohmic region at low fields and high temperatures; a thermally activated field-assisted hopping process (Poole-Frenkel mechanism) at high fields and moderate to high temperatures; an intermediate region between the former two in which space charge effects are noticeable; and a virtually temperature-independent high field process due to some form of tunnelling which prevails at very low temperatures. T.S.C. results show up to five separate peaks with different activation energies, two of which are identified as ionic, two are attributed to electronic hopping and one is associated with space charge injection. A mechanism of hopping conduction is proposed to explain these results and to link with the d.c. Poole-Frenkel process. There is correlation with a.c. results reported earlier on the same material. © 1969.