Influence of thermal treatment on electrical properties of transparent TiO2:Nb thin films

摘要

This study presents electrical behavior of TiO2:Nb thin films with niobium concentration up to 13 at. %. The layers were deposited on Corning 7059 glass substrates by unipolar dc pulse magnetron co-sputtering from TiO2 and Nb composite target. Manufactured films underwent thermal treatment in the ambient air up to the 873 K. Dependencies between the temperature and electrical conductivity as well as thermoelectric force were determined within the range of 300-578 K. An amorphous TiO2:Nb films with optical transparency of about 50% in the visible range and resistivity higher than 8 Ωcm were achieved directly after deposition for the target power density discharge in the range of 4.7-5.8 W/cm2. During the post process air thermal treatment a rapid resistivity decrease (over 1000×) was observed up to final value of 1.5×10-3 Qcm at 300 K. Moreover the conversion from n-type semiconductivity to metallic conductivity was observed. Simultaneously the layers exhibited the substantial increase in the transparency and decrease in Seebeck coefficient from -160 μV/K to -35 μV/K. Electrical behavior of the films where examined with the use of NiCrSi/Ag thin films contacts pads according to Kelvin method.