Dynamic control of light-induced piezoelectricity enhancement in BiFeO3

초록

Piezoelectricity, the electromechanical effect arising from the conversion between mechanical and electrical energy, is a fundamental functionality in ferroelectric perovskite oxides that often exhibit semiconductor behavior. Traditionally, enhancing piezoelectricity has relied on complex synthetical approaches to induce morphotropic phase boundaries, requiring precise structural engineering. However, external stimuli offer a more direct and in situ means of control without prior processing constraints, while also maintaining compatibility with other functionalities. Here, we demonstrate that light serves as a powerful external stimulus to enhance the piezoelectric properties of BiFeO₃?a perovskite semiconductor?within both single crystals and thin films. Through piezoresponse force microscopy and conductive atomic force microscopy, we reveal a significant enhancement in the effective piezoelectric coefficient, dzz, showing up to an eightfold increase under illumination. This enhancement is attributed to the interplay of the bulk photovoltaic effect and Schottky barrier modulation, which influence the open-circuit voltage and photocharge carrier density. Additionally, light polarization-dependent measurements reveal a sinusoidal variation in piezoelectricity closely linked to photocurrent modulations, further amplifying dzz. Temporal decay studies indicate a persistent enhancement even after light removal, associated with the reemission of trapped photocarriers. These findings provide crucial insights into light-induced piezoelectricity enhancement in ferroelectric perovskite semiconductors, paving the way for their integration into multifunctional optoelectronic and nanoelectronic applications.