Elucidating and Monitoring Nano-Sized Effects in ZnO Nanowires for Piezoelectric Applications – IMINEN

ZnO nanowires have been receiving a considerable interest for many application fields including that of piezoelectricity, but crucial, fundamental issues still remain untreated and strongly limit their integration into real applications. The IMINEN PRC project aims at elucidating and monitoring nano-sized effects on several properties of ZnO nanowires, including their piezoelectric coefficients, their compensating doping, their O or Zn polarity and its uniformity, and their surfaces for piezoelectric applications. The active structure consists of ordered arrays of resistive, unipolar, n-type ZnO nanowires with an ultimate, low and uniform diameter down to 10 nm and an aspect ratio up to 100 for boosting the output voltage generated under mechanical stress. The project relies on the innovative development of simulation tools (e.g. finite element method), advanced technological processes in a cleanroom environment (e.g. electron beam & copolymer block lithography), chemical synthesis (e.g. chemical bath deposition), advanced characterizations at macroscopic and nanometre scales using both laboratory- and large-scale facility techniques, and integration, in order to reveal the dependence of the piezoelectric coefficients, the compensating doping, the polarity, and the surfaces on the diameter of ZnO nanowires ranging from 10 to 100 nm. This project gathers the unique and very complementary skills of LMGP, LTM, Institut Néel, LETI, and LGEF to address the fundamental issue related to nano-sized effects, which is still unexplored despite its critical importance.