Thermopower measurements on SiO _x thin films

Abstract

Thermopower and d.c. electrical conductivity measurements have been carried out between 125 and 625 K on SiO _x thin films, 130 nm thick, deposited on to Corning 7059 substratesin vacuo ≃ 1 mPa at 1.5 nm sec⁻¹. The thermopower, d.c. conductivity and their respective activation energies are fitted to a polynomial expression in 1/T. Below 400 K, the thermopower is negative, at 400 K the thermopower activation energy is approximately zero and the dominant current carriers are holes at the valence band edge, between 400 and 470 they are polaronic holes, between 470 and 590 K non-polaronic holes, and above 590 K electrons. Energy band diagrams are proposed for each temperature range studied.