Electroluminescence From Individual ZnO Microwires

The demand for micro-nano optoelectronic devices is even more urgent with the rapid development of optoelectronic integration,optical interconnection and optical integration.As one of the II-VI group semiconductors,ZnO has a direct wide band gap of 3.37 eV,a large exciton binding energy of 60 meV.Besides the above characters,ZnO is abundant,inexpensive,and bio-compactible.Additionally,ZnO has rich micronano structures,which promises that ZnO can be potentially applied in nanoscale light sources.Various micro-nano structures like microwires,microtubes,microbelts,nanowires,nanotubes,quantum dots and so on have been synthesized from ZnO,the a series of optoelctronic devices have been fabricated from the micro-nano structures.In this thesis,we aim to develop microscale light-emitting devices from ZnO micro-nano structures,and the following results have been achieved:1.Single crystalline Ga-doped ZnO microwires(ZnO:Ga MW)with different Gadoping concentrations have been synthesized using a one-step chemical vapor deposition method.Strong electrically driven light emission has been observed from the individual Zn O:Ga MWs.Increasing Ga-doping concentration in the MWs can lead to the redshift(from 490 nm to 700 nm)of the electroluminescence.The mechanism for the emission has been ascribed to heat-assited ionized process of carriers in the microwires.2.Au nanoparticles have been coated onto the individual ZnO:Ga MWs,it is found that the nanoparticles can affect the electroluminescence of the MWs greatly.And controllable periodic array of two-color luminescence was obtained by coating the Au nanoaprticles periodically onto the MWs.The mechanism for the Au nanoparticle adjusted electroluminescence can be understood in terms of the surface plasmon of the nanoparticles.3.Sb-doped ZnO microwires have also been synthesized using CVD method,and the MWs have been placed onto n-type ZnO films to form p-n junctions,and obvious UV emission can be observed from the junctions.