Nanomechanical and Morphological Characterization of Tungsten Trioxide (WO3) Thin Films Grown by Atomic Layer Deposition

This study investigates the nanomechanical properties and surface morphology of tungsten oxide (WO3) thin films deposited on p-type Si (100) substrates using atomic layer deposition (ALD) technology with 2000 ALD deposition cycles at a growth temperature of 300 degrees C and annealed at different temperatures. The samples were further furnace annealed at 500, 600 and 700 degrees C for 60 min. The influence of the deposition process on the structure and properties of the WO3 films is discussed, presented and correlated to the characteristic features of the ALD technique. The results depict significant difference in the hardness and modulus measurements between the as deposited sample and the annealed ones. The hardness and modulus drop from 14 and 170 GPa for the as deposited sample to 10 and 140 GPa for the annealed ones respectively. Surface roughness was observed to increase with annealing temperature and the initially amorphous as deposited sample reached complete recrystallization and transformed into polycrystalline films as indicated by XRD. (C) The Author(s) 2015. Published by ECS. All rights reserved.