Study of thin chemical vapour deposited tungsten oxide films by positron annihilation spectroscopy

The positron lifetime technique has been used to study the relationship bet ween the structure of chemical vapour deposited tungsten oxide thin films a nd the deposition parameters. Some of the positron annihilation characteris tics have been evaluated for WO3 bulk material. The positron annihilation l ifetime results show that there is no saturation trapping and that a consid erable part of positrons annihilate from the free state. Pick-off annihilat ion of orthopositronium localized in two kinds of voids is observed. The gr owth of deposition temperature decreases the disordered material fraction. The increase in total gas flow rate leads to a decrease of large void sizes . (C) 1999 Elsevier Science S.A. All rights reserved.