| Exploring new energy resources is critical for sustainable development of all mankind as global warming and energy crisis.From the macrocosm,new resources,such as optical energy,thermal energy and wind gradually replace petroleum and coal.In microcosm,the properties of independence,safety,biocompatibility,sensitivity and portability take into account.Profiting from its micro-scale,nanodevices are widely used in the field of integrated circuits,sensors,memories,biological implants and nanorobots.This study focuses on the application of metal-oxide materials-based individual micro/nanowire.Two-ternimal devices were fabricated to reclaim thermal resource and mechanical energy from environment and further applied into nanogenerators,tunable resistance switches and programmable multibit non-volatile random access memories.For the nanodevices of thermal-to-electrical energy conversion,their usually have two types: thermoelectric generators and pyroelectric generators,which rely on the temperature difference in time or space.To solve this problem,thermal-generators,based on two-terminal devices of individual Zn2-xSnO4 micro/nanowires,are firstly fabricated to harvest thermal energy and then convert into electricity.The temperature-driving thermalgenerators can generate a stable DC signal as long as they are driven at a constant temperature.They are different from conventional pyroelectric and thermoelectric generators which need the presence of temperature change in time and space,respectively.Their output currents can reach a maximum in the temperature range from 207 to 300 oC.Moreover they can be enhanced by paralleling of the generators.Additionally,the generators can be served as a self-powered system to drive a negative-temperature-coefficient thermistor.The energy conversion could be ascribed to the presence of Femi level difference due to the decrease of the stoichiometric ratio of Zn to Sn along the growth direction of Zn2-xSnO4 micro/nanowire.Therefore,the tilted energy band can make thermal-excited trap electrons quickly transfer toward the rich-Zn initial growth end with a low ionization energy.Those generators,effectively working without temperature variation both in time and space,will have successful applications in powering nanodevices.In the field of memories,currently,nanostructure-based random access memories(RAMs)mainly focus on the electircal information setting.Here,nonvolatile multibit thermalresistive RAMs(TRAMs),which are dual-written/erased by different temperatures or drain-source biases,are realized successfully in individual ZnO:K,Cl micro/nanowire based two-terminal devices.The incorporation of KCl in ZnO lattice creates abundant defects,which can serve as trap centers and store charges.At relatively high temperature,the trapped charges can escape under a low operation voltage,and moreover the depth of emptied trap is dependent of loaded temperature.At relatively high bias,subsequently,electrons can inject into trap states under a low operation temperature,and moreover the depth of filled trap depends on applied voltage.Due to trap states can be empty or filled via thermal excitation or electric field injection of electrons,multibit information can effectively be dual-written/erased by different temperatures or biases.Two-terminal devices based on individual ZnO:K,Cl micro/nanwire gives a direction to the development of gaint thermal resistance and novel nanodevices in rewritable nonvolatile temperature and bias information sensors and memories.Most actively tunable Schottky diodes tend to set up gate voltages or complex configurations.In this work,gate-free two-terminal devices based on individual ZnO:In micro/nanowire back-to-back diodes were fabricated for nonvolatile bias sensors and multibit memories,which can controllable by drain-source bias voltage(VDS).The nonvolatile sensors and multibit memories dominantly originate from the controllable modulation of trap-related Schottky barrier height by the synergistic action of thermal excitation and electric field injection of electrons.Tubable electrical properties of individual ZnO:In micro/nanowire-based two-terminal devices,regulated by temperature and VDS,point a way to develop a new type of nonvolatile bias sensors and multibit resistance random access memories with superior repeatability and stability.For most piezoresistive materials,mechanical action always company with resistive transformation,which usually is applied to strain sensing.However,implementing nonvolatile stress-set memory in such materials is still a challenge.Herein,individual Zn O:In micro/nanowire based two-terminal devices are prepared on flexible substrates,where memory effect can be achieved by capturing and releasing electrons in traps.Moreover,various resistance state sensing and memory can also be controlled by coupling stress and electric field... |
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