Crystal Growth of PZT Thin Film on Combination with Metal Electrode and Conductive Oxide Layer

Abstract

A pyroelectric infrared sensor detects a pyroelectric current caused by the temperature rise of a Pb(Zr_x, Ti_1-x)O₃ (PZT) film due to irradiation of infrared rays. However, the temperature rise of PZT is suppressed when heat is transferred from an electrode of the sensor, and the sensitivity is lowered. For reducing the thermal conductivity of electrodes, a SrRuO₃ (SRO) film was used as the electrode of the PZT film. Pt/Ti multilayer films were formed on the SRO film to prevent the PZT film from being dissolved by wet etching. The film thickness of Pt was 10 and 50 nm, and the film thickness of Ti was 0, 2, and 30 nm. In the case that the PZT film was formed on the 10 nm Pt/SRO film, the average grain diameter of this PZT film was 1 µm, and the crystal orientation was random. Also, the residual polarization (2P_r) was approximately 37 µC/cm², and the pyroelectric coefficient was approximately 400 µCK^-1m^-2.