Sol-gel derived Pb(Zr,Ti)O3 thin films on GaAs

Sol-gel derived thin films of lead zirconate titanate (PZT) have been fabricated on a platinized GaAs substrate using a propane-1,3-diol based sol-gel route. PZT can be used as the piezoelectric component in bulk acoustic wave devices for monolithic microwave integrated circuit applications. A 100 nm silicon nitride buffer layer was deposited onto the GaAs by plasma-enhanced chemical vapour deposition in order to prevent gallium and arsenic outdiffusion during film fabrication. Rapid thermal processing (RTP) techniques were employed to decompose thermally the sol-gel layer to PZT in a further effort to minimize problems of gallium and arsenic outdiffusion. Adhesion between the bottom electrode and substrate was found to improve when an intermediate titanium layer deposited between the platinum and silicon nitride was oxidized prior to deposition of the platinum electrode. A crystalline PZT film was produced on the Pt/TiO2/Si3N4/GaAs substrate configuration by firing the sol-gel coating at 650 degrees C for 10 s using RTP. A single deposition of sol resulted in a film having a thickness of 0.5 mu m. Ferroelectric hysteresis measurements yielded average values of remanant polarization and coercive field of 14 mu C cm(-2) and 47 kV cm(-1) respectively.