How Can InGaN/GaN Heterostructures Be Advantageous for the Piezoelectric Conversion of GaN Nanowires and their Applications?
Résumé
The IoT demands for smart, integrated, miniaturized and low-energy wireless devices are constantly on a rise both in our daily life and in high-tech applications and the question of their energy suppling is now a key worldwide challenge. Nanowires (NWs)-based piezoelectric nanogenerators have appeared these last years as a new solution for replacing the batteries by converting the environmental vibrations into electrical energy. While these new energy sources have demonstrated power densities in the µW-mW/cm3 range, their use as micro-system power supply working under environmental conditions remains today rather limited. To consider them for supplying micro-devices, the improvement of the conversion efficiency per surface unit of the piezoelectric active layer is a prerequisite. We demonstrated that by integrating In0.35Ga0.65N thick homogeneous insertion in the GaN NW volume, we improved the piezoelectric response of the GaN NWs [1] due to the higher piezoelectric coefficients of InGaN [2].
An increase of the power density of about 20% in presence of InGaN is highlighted, both at nano-and macro-scales studied under environmental-like solicitation conditions (few Newton, 1-100 Hz). At macro-scale, a maximum power density of 3.2 µW/cm² (23.1 mW/cm3) was reached under intermittent contact solicitation, with a maximum peak-to-peak output voltage attaining 143 mV. This enhancement allows us to approach the power requirements of microelectronical systems, such as medical implants (1µW-10µW).
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