Hydrogen effect on structure and mechanical properties of ZnO films deposited in Ar/H2 plasma

In the present work the mechanical properties of the ZnO thin films deposited on Si (100) substrates, were studied using a nanoindentation. The thin films of ZnO were deposited by radiofrequency sputtering with different H2/Ar gas mixture. During the deposition the species of the plasma were in situ monitored using optical emission spectroscopy. The results showed a strong effect of H2 on film hardness and elastic modulus. Using the correlation between the elastic modulus values and materials porosity in the ceramic the porosity of the ZnO was estimated . We found an increased film porosity when H2 is added to the sputtering gas, from 4% to 16% volume. Moreover we found that the porosity could be controlled by the emission intensity ratio of atomic Argon on atomic Hydrogen.