Femtosecond Laser-induced Growth Of Zinc Oxide Patterns And Fabrication Of Micro/Nano UV Detector

With the development of physics,chemistry and and semiconductor microelectronics technology,mankind has made unprecedented breakthrough in exploring the micro-nano scale world.The most intuitive manifestation is the continuous maturity of integrated circuits.However,the development of“Moore’s Law”has approached the bottleneck.The traditional silicon integrated circuit preparation process is not suitable for many other semiconductor materials with excellent properties due to the limitations of process parameters and preparation temperature.In order to pursue smaller size and more efficient chip performance and realize flexible and efficient integration of various functional devices on the chip,researchers are required to develop new technologies to manufacture micro-nano integrated devices with excellent performance.Among all kinds of high-performance materials,zinc oxide(ZnO)is a promising transparent metal oxide with a band gap of 3.37 e V at room temperature and exciton binding energy as high as 60 me V,which is one of the most widely used materials in the field of ultraviolet optoelectronic devices.At present,the fabrication methods of ZnO micro-nano structure,such as hydrothermal method and molecular beam epitaxy,usually require extreme preparation conditions,and it is difficult to form any patterned micro-nano structure.In this paper,by using femtosecond laser direct writing method and the interaction between laser and sol-gel precursor,ZnO structures with arbitrary patterns can be synthesized on the substrate in a single step and efficiently,and micro-nano devices can be fabricated.The main work is as follows:(1)Based on the principle of sol-gel method,the precursor solution for femtosecond laser direct writing is prepared.After the precursor undergoes spin coating,femtosecond laser direct writing and cleaning steps,ZnO samples generated by reaction are left on the substrate.In the process of laser direct writing,complex patterned ZnO products can be obtained by controlling the movement of piezoelectric displacement stage or laser focus.Absorption spectrum test shows that multiphoton absorption occurs when femtosecond laser direct writing precursor solution.The products produced by laser direct writing were directly tested by secondary ion mass spectrometry,and the test results proved that the composition of the products is ZnO.(2)In order to solve the problem of discontinuous product morphology in the process of femtosecond laser direct writing ZnO,glycerol was added into the precursor solution as a functional additive.In the process of femtosecond laser direct writing after adding glycerol additive,with the increase of glycerol content,the morphology of ZnO products became more and more flat and compact,and the particle size of products was uniform,and the surface roughness gradually decreased.It is found that the effect of glycerol on the whole system is mainly divided into two aspects:one is to inhibit the hydrolysis and polycondensation of solute in the precursor and control the nucleation size of ZnO crystals;Secondly,glycerol molecules are cross-linked with each other through hydrogen bonds,so that the viscosity of precursor solution is improved,and the solute moving rate is reduced;And the growth speed of the nucleated ZnO particles is controlled under the coating action of glycerol,so that the product particles after laser direct writing are uniform in size and controllable in morphology.(3)The fabrication of ZnO micro-nano ultraviolet photoelectric detector with femtosecond laser direct writing was realized,and its photoelectric response performance to ultraviolet light with wavelength of 365 nm was tested.The effect of glycerol additive on the performance of ZnO micro-nano devices was studied.The experimental results show that the light/dark current switching ratio of devices can be increased from 10~2 to 10~5 when20%glycerol is added into the precursor solution.The chemical mechanism of glycerol improving ZnO morphology and improving device performance was also explored.The test results show that ZnO micro-nano devices written directly by femtosecond laser have great application potential in the field of ultraviolet detection.In this work,femtosecond laser direct writing technology is used to realize the single-step high-precision patterned fabrication of ZnO nanomaterials under various substrate conditions,and glycerol additives are used to improve the product morphology of ZnO and the performance of micro-nano devices,which broadens the road for the application of ZnO in ultraviolet optoelectronic devices and other fields.