Temperature induced change in the hysteretic behavior of the capacitance-voltage characteristics of $Pt–ZnO–Pb(Zr0.2Ti0.8)O3–Pt$ heterostructures

$Pt–ZnO–Pb(Zr0.2Ti0.8)O3–Pt$ (PZT-ZnO) heterostructures were fabricated by using a sol-gel process. Capacitance-voltage measurements performed on a wide temperature range (20–450 K) have revealed the presence of a hysteresis that undergo a change of direction from clockwise at temperatures below 350 K to counter-clockwise at higher temperatures. In the first case, the hysteresis is produced by charge injection, similar to the case of classical metal-oxide-semiconductor capacitors. In the last case, the hysteresis is the fingerprint of polarization reversal, as reported for metal-ferroelectric-semiconductor (MFS) structures based on n-Si. The memory window at 450 K is about 6 V. This result suggests that PZT-ZnO MFS heterostructures can be used for memory devices working at elevated temperatures, in which the ZnO plays the role of the semiconductor.