Strain-Gated Piezotronic Logic Nanodevices

www.MaterialsViews.com C O M Strain-Gated Piezotronic Logic Nanodevices M U N By Wenzhuo Wu , Yaguang Wei , and Zhong Lin Wang * IC A IO N A self-powered [ 1 ] autonomous intelligent nanoscale system should consist of ultrasensitive nanowire (NW) based sensors, [ 2–5 ] integrated high-performance memory and logic computing components for data storage and processing as well as decision making, [ 6–12 ] and an energy scavenging unit for sustainable, self-suffi cient, and independent operation. [ 1 , 13–20 ] The existing semiconductor NW logic devices are based on electrically-gated fi eld-effect transistors, which function as both the drivers and the active loads of the logic units by adjusting the conducting channel width. [ 22 , 23 ] Moreover, the currently existing logic units are “static” and are almost completely triggered or agitated by electric signals, while the “dynamic” movable mechanical actuation is carried out by another unit possibly made of different materials. Here, we present the fi rst piezoelectric triggered mechanicalelectronic logic operation using the piezotronic effect, through which the integrated mechanical electrical coupled and controlled logic computation is achieved using only ZnO NWs. By utilizing the piezoelectric potential created in a ZnO NW under externally applied deformation, strain-gated transistors (SGTs) have been fabricated, using which universal logic components such as inverters, NAND, NOR, XOR gates have been demonstrated for performing piezotronic logic calculations, which have the potential to be integrated with the NEMS technology for achieving advanced and complex functional actions in applications of vital importance in portable electronics, medical sciences and defense technology, such as in nanorobotics for sensing and actuating, in microfl uidics [ 24 ] for controlling the circuitry of the fl uid fl ow, in other micro/nano-systems for intelligent control and action. ZnO is unique because of its coupled piezoelectric and semiconductor properties, which is the piezotronic effect dealing with the piezoelectric potential (piezopotential) tuned/gated charge carrier transport process in a semiconductor material. [ 25–27 ] The piezopotential created inside a ZnO NW under strain can be effectively used as a gate voltage, which has been applied for fabricating a range of piezotronic nanodevices, [ 26 , 28 ]