Sol-gel synthesis of PZT thin films

Summary form only given. Information is presented on a diol based sol-gel route for the fabrication of PZT thin films in the thickness range 0.5-10 microns. Crystallisation and ferroelectric properties have been measured as a function of film thickness and firing temperatures for PZT (53/47) films deposited on 111-Pt/Ti/SiO₂/Si substrates. The results highlight the complex interrelationships between film properties and the thermal history of the film/electrode/substrate stack. The films generally exhibit 111 preferred orientation due to heterogeneous nucleation and growth from the electrode-film interface. However the type and extent of preferred orientation may be influenced by reactions occurring at low temperatures between the platinum electrode and the underlying Ti adhesion layer, and because of reactions between the electrode and the PZT layer. Results for the 53/47 films illustrate, as expected, an overall decrease in preferred orientation with increasing film thickness. The increase in remanent polarisation and decrease of measured coercive field with increasing film thickness are considered to be due to a combination of changes in preferred orientation and stress levels, together with a proportionately reduced effect of the low permittivity interfacial phases. Further information on the interrelationship between crystallite orientation and measured ferroelectric parameters has been obtained by investigating film compositions away from the morphotropic phase boundary in order to eliminate the possibility of di-phasic structures that complicate data analysis. Finally, preliminary results for a new sol-gel system are commented upon