Stable and High Piezoelectric Output of GaN Nanowire-Based Lead-Free Piezoelectric Nanogenerator by Suppression of Internal Screening

Abstract

A piezoelectric nanogenerator (PNG) that is based on c-axis GaN nanowires is fabricated on flexible substrate. In this regard, c-axis GaN nanowires were grown on GaN substrate using the vapor-liquid-solid (VLS) technique by metal organic chemical vapor deposition. Further, Polydimethylsiloxane (PDMS) was coated on nanowire-arrays then PDMS matrix embedded with GaN nanowire-arrays was transferred on Si-rubber substrate. The piezoelectric performance of nanowire-based flexible PNG was measured, while the device was actuated using a cyclic stretching-releasing agitation mechanism that was driven by a linear motor. The piezoelectric output was measured as a function of actuation frequency ranging from 1 Hz to 10 Hz and a linear tendency was observed for piezoelectric output current, while the output voltages remained constant. A maximum of piezoelectric open circuit voltages and short circuit current were measured 15.4 V and 85.6 nA, respectively. In order to evaluate the feasibility of our flexible PNG for real application, a long term stability test was performed for 20,000 cycles and the device performance was degraded by less than 18%. The underlying reason for the high piezoelectric output was attributed to the reduced free carriers inside nanowires due to surface Fermi-level pinning and insulating metal-dielectric-semiconductor interface, respectively; the former reduced the free carrier screening radially while latter reduced longitudinally. The flexibility and the high aspect ratio of GaN nanowire were the responsible factors for higher stability. Such higher piezoelectric output and the novel design make our device more promising for the diverse range of real applications.

Nanogenerators as a Sustainable Power Source: State of Art, Applications, and Challenges

“…The developed PENG is capable of harnessing energy from the airflow, finger forces, and vibrations at a frequency of 20 Hz. Johar et al (2018) fabricated the GaN (Gallium Nitride)-based piezoelectric nanogenerator using Ni as contact metal [55]. The output performance was enhanced by using polydimethylsiloxane (PDMS) as a dielectric medium between GaN nanowire and Ni electrode.…”

Highly Durable Piezoelectric Nanogenerator by Heteroepitaxy of GaN Nanowires on Cu Foil for Enhanced Output Using Ambient Actuation Sources

“…[ 16–19 ] Among these, GaN is preferred for applications due to its mechanical robustness, biocompatibility, and well‐developed processes for industrial‐scale production. [ 20–23 ] PENGs are fabricated using a variety of geometrical designs such as thin film‐based PENGs [ 20,24 ] and 1D‐based PENGs that include an active medium composed of nanotubes (NTs), [ 25,26 ] nanowires (NWs), [ 27 ] nanorods, [ 28 ] nanosheets, [ 29 ] nanoparticles, [ 30 ] nanobelts, [ 31 ] nanofibers, [ 32 ] and nanocomposites. [ 15 ] Among the above‐mentioned 1D active media used to fabricate PENGs, NWs are the most promising candidates for piezoelectric applications because of their superior mechanical properties, structural perfection due to their defect‐free structure, better strain confinement, and high elastic limit of deformation without plastic deformation.…”

Three-dimensional hierarchical semi-polar GaN/InGaN MQW coaxial nanowires on a patterned Si nanowire template

“…[1][2][3] Nanowires (NWs) are currently being studied in a variety of elds including the elds of optical, 4 electronic, 5 sensing, 6 and energy applications. [7][8][9] To fully exploit all of the potential advantages of NWs, a variety of approaches for the fabrication and characterization of multidimensional composite NWs have been used. [10][11][12] These methods provide opportunities to integrate diverse materials into hierarchical NWs and enable the optimization of the structures in terms of the materials.…”