Giant Flexoelectricity in Silicon via Light‐Sensitive Schottky Junction

Abstract Silicon is the cornerstone material of modern electronics, and has industrialized techniques for achieving large‐scale integration of functional devices. However, the lack of inversion symmetry breaking naturally determines its non‐piezoelectricity, hindering the development of silicon‐based electromechanics. Flexoelectricity induced by strain gradient is a promising way to endow silicon with electromechanical properties, but it is generally too weak to be functionalized in practical applications. Herein, a strategy is proposed to enhance the flexoelectricity of silicon by six orders of magnitude through the combination of a Schottky junction and light modulation. This flexoelectric‐like effect arises from the bending‐induced antisymmetric modulation on the Schottky barrier and the increase in carrier concentration generating by illumination. Under light illumination, the gold‐coated n ‐type silicon yields a flexoelectric coefficient with six orders of magnitude larger than the intrinsic one, reaching a maximum of 1 mC m −1 . A mechanical energy harvester proto‐device is further demonstrates the practicality of flexoelectrically modified silicon. The output normalized power density of the flexoelectric energy harvester is up to 2.5 µW cm 3 g 2 Hz −1 , being comparable to the performance of lead‐free piezoelectric ones. This work exploits the flexoelectricity in silicon, opening possibilities for high‐performance electromechanical applications based on silicon.