Influence of Pt/TiO2 bottom electrodes on the properties of ferroelectric Pb(Zr,Ti)O3 thin films

Pb(Zr,Ti)O-3 (PZT) thin films were deposited onto Pt/TiO2 /SiO2/Si substrates with different-types of TiO2 layers by liquid delivery MOCVD at 550degreesC. Three kinds of TiO2 adhesion layers were examined: 200 oriented TiO2 with rutile structure, 103 oriented TiO2 with anatase structure and randomly oriented TiO2 which consisted of nanocrystals. In the anatase case, the PZT thin film consisted of large tetrapod-like grains with 111 orientation while the PZT film had a 001/100 mixed orientation and consisted of fine columnar grains in the rutile cases. In the nanocrystal case, the orientation was weak and the film consisted of both types of grains. From these results, we concluded that highly oriented TiO2 formed at higher temperature, the rutile TiO2 in this investigation, is the better material for the under layer. However, the remanent polarization of the PZT capacitor with the rutile TiO2 significantly increased with polarization reversal because the PZT film had a 001/100 mixed orientation. Some seeding layer will be required to obtain 111 oriented PZT thin films on Pt/TiO2/SiO2/Si substrates with rutile TiO2.