Accurate models for the current-voltage characteristics of vertically compressed piezo-semiconductive quasi-1D NWs
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Accurate models for the current-voltage characteristics of vertically compressed piezo-semiconductive quasi-1D NWs Rodolfo Araneo1*, Giampiero Lovat1, Christian Falconi2,3, Andrea Notargiacomo4, Antonio Rinaldi5,6 1
DIAEE - Sapienza University of Rome, Via Eudossiana 18, 00184, Rome Department of Electronic Engineering, University of Rome “Tor Vergata”, Via del Politecnico 1, 00133, Rome 3 CNR IDASC, Via Fosso del Cavaliere, 100, 00133 Rome, Italy 4 Institute of Photonics and Nanotechnology – CNR, Via Cineto Romano 42, 00156, Rome , Italy 5 University of L'Aquila, International Research Center for Mathematics & Mechanics of Complex System (MEMOCS), Via S. Pasquale, 04012, Cisterna di Latina (LT), Italy 6 ENEA ,C.R. Casaccia, Via Anguillarese 301, Santa Maria di Galeria, 00123, Rome, Italy 2
ABSTRACT We investigate the electrical transport in quasi-1D piezo-semiconductive NWs under purely vertical compressive or tensile strains. For simplicity, we exclusively consider the additional band bending originated by the piezoelectric charges assumed to be distributed, with a constant volumic density, within a maximum distance piezo from the metal-to-NW junction. Our calculations demonstrate that the carrier concentration, the energy conduction band profile and the I-V characteristics significantly depend on piezo . We therefore propose that I-V measurements can allow to obtain information on piezo in strained piezo-semiconductors. INTRODUCTION Quasi-1D piezoelectric semiconductive nanostructures are being intensively studied because of their outstanding potential [1-6]: they are largely deformed by tiny input mechanical forces, may have substantially higher piezoelectric coefficients, and can withstand extreme deformations without breaking [7], thus allowing the generation of high piezopotentials [1-3,6]. However, the I-V characteristics of quasi-1D piezoelectric nanowires (NW) under a purely vertical compressive or tensile strain have only been computed for a Gaussian doping profile; moreover a standard commercial software has been used [2]. In the present work we develop an ad-hoc numerical model and consider a constant doping profile; our calculations demonstrate that the electrical transport strongly depends on the volumic distribution of the equivalent piezoelectric charges inside the piezo-semiconductive nanowire. In particular, we assume that the piezoelectric charges, which only ideally may be thought as exclusively located at the surface separating the piezo-semiconductive NW from the metal contact, are distributed, with a constant volumic density, within a maximum distance piezo from the metal-to-NW junction. As a representative example, we calculate the carrier concentration, the energy conduction band profile and the I-V characteristics for a ZnO NW with piezo equal to 0.26nm (i.e. half the lattice constant of ZnO along the c-axis that ranges from 0.52042nm to 0.52075 nm [8]) and 0.52nm. We suggest that the significant dependence of the electrical transport on piezo may allow to obtain information
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