Details

Autor(en) / Beteiligte

• Dai, Le
• Liu, Yang
• Gao, Xuan
• Wang, Shuhao
• Song, Yating
• Tang, Mingmeng
• Karpinsky, Dmitry V
• Liu, Lisha
• Wang, Yaojin

Titel

Self-polarization Achieved by Compositionally Gradient Doping in BiFeO3 Thin Films

Ist Teil von

• Wu ji cai liao xue bao, 2024, Vol.39 (1), p.99

Ort / Verlag

Beijing: Chinese Academy of Sciences

Erscheinungsjahr

2024

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• BiFeO3 is a highly promising lead-free ferroelectric material, surpassing most conventional ferroelectric materials in terms of the polarization and Curie temperature, offering a pathway for potential applications at elevated temperatures. Nevertheless, challenges arise due to strong clamping effect of substrate, large coercive fields, and high leakage currents, causing BiFeO3 films difficult to be polarized. The implementation of self-polarization presents a viable solution. Herein, we prepared BiFeO3, up-graded films(which transition from BiFeO3 to Bi0.80Ca0.20FeO2.90 from the substrate to the film surface), and down-graded films(which transition from Bi0.80Ca0.20FeO2.90 to BiFeO3 from the substrate to the film surface) using the Sol-Gel method on Pt（111）/Ti/SiO2/Si substrates. After directional distribution of defects within the film being carefully modulated, the BiFeO3 films are self-polarization when induced by build-in electric field. Piezoresponse force microscopy show that the up-graded and down-graded self-polarization behavior can be modulated by gradient direction of Ca in BiFeO3 thin films. Moreover, diode-like current-voltage signature verifies the composition gradient-induced self-polarization. The X-ray photoelectron spectroscopy results indicate that the polarization orientation mechanism may arise from the internal electric field attributed to the gradient distribution of oxygen vacancy. This work provides a new strategy to achieve self-polarization in ferroelectric thin films, as well potential novel application in improving the performance of photovoltaic or photosensitive devices as assisted by internal field via self-aligned ferroelectric polarization.