Studies On Strain Enhanced Ultraviolet Light Detector And Ultraviolet Light-strain Logic Gated Transisitor Based On ZnO Microwires

Currently,piezotronics and piezo-phototronics on nanomaterials have aroused widespread attention in the global academic community.The wurtzite structure ZnO exhibitting excellent optical properties,semiconductor properties and piezoelectric properties has become one of the representative nanomaterials in the fields of piezotronics and piezo-phototronics.The piezo-optic-electric effects of ZnO on piezo-phototronics devices are mainly based on its ternary coupling to modulate the electrical transport properties of the devices.In this paper,Au nanoparticles(NPs)decorated ZnO microwires(MWs)were successfully fabricated.Using the coupling between piezoelectric potential and localized Schottky barriers(SBs),the electrical transport properties of the ZnO MWs were controlled successfully,and then the proformances of the ZnO MW strain-ultraviolet(UV)light detector(PD),strain-gated-transistor(SGT)and UV light-strain-gated-transistor(LSGT)were enhanced.The main results of this research are listed as below:1.Ultralong ZnO MWs with high crystalline were firstly obtained by chemical vapor deposition,and then coated with Au NPs by ion beam sputtering.Then,this kind of nanostructure was characterized by scanning electron microscope(SEM),transmission electron microscope(TEM)and photoluminescence(PL)in detail.Finally,we chose the ZnO wires with suitable sizes and fixed them tightly on the polyimide substrate,where silver paste was spot-welded at both ends of the MW as electrodes for UV light detectors.Compared to original ZnO MW UV light detector,the dark current of Au NPs decorated detector has a sharper decrease under equivalent strain,thereby the photo-respone of the device was improved.The Au NPs deplete more carriers near the surface of the wire,which raises the SB height and thickens the depletion region,and then desendes the reset time from 142.4 s to 0.7 s.After applying the compressive strain,the obtained piezoelectric potential further raises the SB height,thickens the depletion region and improves photo-response properties of the detector.The dark current of the Au NPs decorated detector is reduced by about 5 orders and its on/off current ratio is increased by about 6 orders,and the recover time of the detector is further reduced to 0.1 s ultimately.2.Based on the coupling of localized SBs formed by Au NPs decorated ZnO MWs and the piezoelectric potential created upon straining,the highly enhanced piezoelectric effect was applied for designing SGTs,which increased the on/off current ratio of the device and modulate the charge carrier transport at the ZnO/metal contact.The SGTs contains inverter,NAND,AND,NOR,OR,XOR gates and 2:1 MUX for a series logic computations.Moreover,the piezo-phototronic effect of the Au NPs decorated ZnO MWs was also applied to design LSGTs processing mechanical and optical stimuli into electronic controlling signals,and modulated the process of generation,transmission and composite behavior of the carrier at the ZnO/metal contact.Logic computation of NAND,AND,NOR,OR,and XOR gates with good rectifying behaviors were fulfilled in these LSGTs.In a word,this work suggests a viable approach to get Zn O MW pizeo-phototronic devices with high on/off ratio,ultrafast response speed and low power consumption,which helps understand the coupling effect among piezoelectric properties,semiconductor properties and optical properties of ZnO.The piezo-phototronic devices show potential applications in active flexible electronics,medical science and defence-related science and technology,such as nano-robots,and control in the fluid flow of microfluidic circuit and other micro-nano system used in intelligent control operation.