Cu2O Heterostructured GaN Thin Film and GaN Nanowire Piezoelectric Nanogenerators

Herein, a c‐plane GaN thin film (TF) and c‐axis GaN nanowires are grown using metal‐organic chemical vapor deposition (MOCVD) and then utilized in the fabrication of piezoelectric nanogenerators (PENGs). The piezoelectric performance of GaN‐based PENGs is tuned by sputtering a resistive layer of Cu2O on GaN TFs and nanowires. A significant enhancement in the piezoelectric output of a Cu2O‐coated GaN TF‐based PENG is observed compared with that of a pristine GaN TF‐based PENG. The enhanced output is attributed to the high resistivity of Cu2O, which is controlled by conducting Cu2O sputtering in “0” sccm oxygen flow. Furthermore, a GaN/Cu2O core–shell nanowire‐based PENG is fabricated to enhance the flexibility and stability of nanogenerators. A GaN/Cu2O core–shell nanowire‐based piezoelectric nanogenerator (NW‐PENG) exhibits enhanced flexibility, stability, and piezoelectric output voltage. Cu2O with optimized resistivity is sputtered on metal‐organic chemical vapor deposition (MOCVD)‐grown c‐axis GaN NWs. To enhance the stability and flexibility of the NW‐PENG, the core–shell NWs are encapsulated in polydimethylsiloxane (PDMS) and transferred to an indium tin oxide (ITO)‐deposited flexible poly(ethylene terephthalate) (PET) substrate.