Mechanical Manipulation of Electrical Behaviors of Piezoelectric Semiconductor Nanofibers by Time-Dependent Stresses
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ISSN 1860-2134
Mechanical Manipulation of Electrical Behaviors of Piezoelectric Semiconductor Nanofibers by Time-Dependent Stresses Haoyu Huang1
Zhenghua Qian1
Jiashi Yang2
1
( State Key Laboratory of Mechanics and Control of Mechanical Structures, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China) (2 Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA)
Received 23 March 2020; revision received 8 July 2020; Accepted 13 July 2020 c The Author(s) 2020
ABSTRACT We study electric currents in a piezoelectric semiconductor fiber under a constant voltage and time-dependent axial stresses applied locally. From a nonlinear numerical analysis based on a one-dimensional phenomenological model using the commercial software COMSOL, it is found that pulse electric currents can be produced by periodic or time-harmonic stresses. The pulse currents can be tuned by the amplitude and frequency of the applied stress. The result obtained provides a new approach for the mechanical control of electric currents in piezoelectric semiconductor fibers and has potential applications in piezotronics.
KEY WORDS Piezoelectric semiconductor nanofiber, Tunable pulse electric current, Timedependent stress, Piezotronics
1. Introduction Many new piezoelectric semiconductor nanostructures, e.g., ZnO fibers, belts, spirals, tubes and films, have been synthesized in the last one to two decades [1–3]. They have been used to make various electromechanical devices such as energy harvesters, mechanically-gated transistors, acoustic charge transport devices, and physical as well as chemical sensors [4–8]. Piezoelectric semiconductors are also used in quantum wells, dots and wires [9]. The research on piezoelectric semiconductor materials and devices has been growing steadily [10]. It has formed a new research area called piezotronics and piezophototronics [11–14]. In piezotronic devices, the motion of charge carriers is manipulated by mechanical loads through the accompanying electric field due to piezoelectric coupling. Many piezotronic devices are made from ZnO nanofibers with PN or MS junctions [14]. These fibers may be in extensional [15–19] or bending [20–24] deformations, which affect the current–voltage relations (I–V curves) of the junctions. Recently, it has been shown that local extensional/compressive stresses in a piezoelectric semiconductor fiber produce electric potential barriers/wells [25, 26], which affects the I–V curves of the fiber even without the presence of PN or MS junctions. This offers a new means for the mechanical tuning of electrical behaviors of piezoelectric semiconductor fiber devices. The same effect also exists in piezoelectric semiconductor fibers under a local temperature change [27]. In [25, 26], the local stresses
Corresponding author. E-mail: [email protected]
ACTA MECHANICA SOLIDA SINICA
are static. They act like a stress-dependent switch in a semiconductor fiber. Under a fixed voltage, current can flow
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