Thickness-Driven Aluminum Nitride-Based Piezotronic Device for Concurrent Energy Harvesting and Sensing

Abstract

Piezotronic devices have emerged as a potential candidate that offers promising platforms for sustainable energy harvesting and self-powered devices. Such devices employ strain-induced piezoelectric polarisation charges as a gate voltage to tune the charge carrier transport at the interface. Leveraging this mechanism, an aluminum nitride (AlN)-based piezotronic devices are fabricated on silicon substrate using the direct current (DC) sputtering technique. Herein, AlN film thickness is utilised as a key factor to modulate the output voltage and electronic characteristics. An increase in film thickness from 0.8 to 1.6 µm results in an enhancement in crystallite size from 19.35 to ∼23 nm, c-axis orientation, and columnar growth. The fabricated piezoelectric nanogenerators (PENGs) demonstrate noticeable improvement, achieving a maximum voltage of ∼0.6 V and sufficient current to charge capacitors of various capacitances (1 to 22 µF). The energy conversion efficiency of 42.93% ± 0.52% and power density of 11 nW/cm2 is achieved in device having 1.6 µm thick film, surpassing conventional AlN-based PENGs that typically suffer from low output voltage and poor interface quality. Simultaneously, piezotronic sensing improves, with Schottky barrier modulation of ∼17.16 meV and gauge factor of ∼73.65 × 103. These results establish that thickness-driven AlN-based devices are a potential candidate for next-generation self-powered applications.