Temperature-dependent optical and surface electrical properties of Pb(Zr0.3Ti0.7)O3 /p-GaN film

Understanding the temperature-dependent optical and electrical properties of PZT, a multifunctional ferroelectric thin film with temperature sensitivity, is crucial for its applications. This study systematically investigated the microstructure, optical, and surface electrical features of Pb(Zr 0.3 Ti 0.7 )O 3 thin film deposited on p-GaN substrate (PZT/p-GaN), with an emphasis on their response to temperature variations. Band gap energy (3.643 eV) and the three interband electronic transitions (3.528 eV, 4.662 eV, 6.582 eV) were extracted from optical measurements, which govern the photoelectron transmission behavior of the PZT/p-GaN. Additionally, we identify three phase-transition temperatures (450 K, 550 K, and 620 K) through temperature-dependent optical behavior analysis. With increasing temperature, the electronic transitions and bandgap show a redshift trend, and the bandgap change follows the O'Donnell equation with a significant electron-phonon coupling coefficient (S = 10.284), revealing a strong electron-phonon coupling effect in PZT/p-GaN. The temperature-dependent kelvin piezoelectric force microscopy (KPFM) shows that the surface potential and work function of PZT/p-GaN exhibit different linear variations over three temperature ranges divided by the phase transition temperature point as a demarcation. Furthermore, we observed that the optical and surface electrical properties exhibit anomalous trends at the phase transition point. These findings offer a theoretical reference for the application of PZT thin films in optoelectronics and electronic devices.