Optical and electrical characterisation of Ta2O5 thin films for ionic conduction applications

This paper reports on the optical and electrical characterisation of Ta2O5 thin films deposited by electron beam evaporation from sintered ultrapure Ta2O5 powders as source. The substrates were fused silica and aluminium-coated Si wafers to allow optical and electrical analysis respectively. Two samples were grown at temperatures of 100 degrees C and 200 degrees C, at partial O-2 pressure of 5 x 10(-2) Pa and thickness of 0.65 mu m and 1.25 mu m respectively. The analysis pointed out that the two samples showed high electrical resistivity and that no noticeable optical absorption in the visible spectrum was found. Complex dielectric functions, electrical field breakdown, optical transmittance and direct gap measurements were made to provide minimum quality standards to produce Ta2O5 films for electro-optical devices. (C) 1999 Elsevier Science S.A. All rights reserved.