High Piezoelectric Conversion Properties of Axial InGaN/GaN Nanowires

• Main Authors: Nikoletta Jegenyes, Martina Morassi, Pascal Chrétien, Laurent Travers, Lu Lu, Francois H. Julien, Maria Tchernycheva, Frédéric Houzé, Noelle Gogneau
• Format: Article
• Language: English
• Published: MDPI AG 2018-05-01
• Series: Nanomaterials
• Subjects: III-N nanowires; piezoelectric generation; atomic force microscope; piezo-generators; energy harvesting
• Online Access: http://www.mdpi.com/2079-4991/8/6/367

We demonstrate for the first time the efficient mechanical-electrical conversion properties of InGaN/GaN nanowires (NWs). Using an atomic force microscope equipped with a modified Resiscope module, we analyse the piezoelectric energy generation of GaN NWs and demonstrate an important enhancement when integrating in their volume a thick In-rich InGaN insertion. The piezoelectric response of InGaN/GaN NWs can be tuned as a function of the InGaN insertion thickness and position in the NW volume. The energy harvesting is favoured by the presence of a PtSi/GaN Schottky diode which allows to efficiently collect the piezo-charges generated by InGaN/GaN NWs. Average output voltages up to 330 ± 70 mV and a maximum value of 470 mV per NW has been measured for nanostructures integrating 70 nm-thick InGaN insertion capped with a thin GaN top layer. This latter value establishes an increase of about 35% of the piezo-conversion capacity in comparison with binary p-doped GaN NWs. Based on the measured output signals, we estimate that one layer of dense InGaN/GaN-based NW can generate a maximum output power density of about 3.3 W/cm2. These results settle the new state-of-the-art for piezo-generation from GaN-based NWs and offer a promising perspective for extending the performances of the piezoelectric sources.