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We demonstrate the high potential of GaN nanowires (NWs) to convert mechanical energy into electric energy. Using an atomic force microscope equipped with a Resiscope module, an average output voltage of -74 mV and a maximum of -443 mV ± 2% per NW were measured. This latter value is the highest reported so far for GaN NWs. By considering these output signals, we have estimated an average and a maximum power density generated by one layer of GaN NWs of the order of 5.9 mW/cm2 and 130 mW/cm2, respectively. These results offer promising prospects for the use of GaN NWs for high-efficiency ultracompact piezogenerators. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The semiconductor nanowires (NWs) presenting piezoelectric properties have recently emerged as excellent candidates to fabricate novel and efficient piezoelectric generators through the harvesting of mechanical deformations and vibrations energies. In particular, gallium nitride (GaN) NWs are characterized by both higher piezoelectric response and output voltages with respect to other piezoelectric material NWs. In their Letter on pp. 414–419, Noelle Gogneau et al. investigate the mechanical–electrical conversion of GaN NWs. An average output voltage of about –74 mV for a large NW ensemble and a maximum output voltage reaching –443 mV (±2%) per NW are demonstrated. This latter output voltage is the highest value reported so far for GaN NWs. Based on these measured output signals, an average and a maximum power density generated by one layer of GaN NWs of the order of 5.9 mW/cm2 and 130 mW/cm2, respectively, have been estimated. This result evidences the strong potentiality of GaN NWs to develop ultra‐compact and integrable renewable energy source for sustainable, independent and maintenance‐free operation of microdevices. [ABSTRACT FROM AUTHOR]