Research On Nanoimprinting Of Photoelectric Micro-devices

In the semiconductor industry,patterning technology is very important.With the development of high miniaturization and integration of integrated circuits,as the core technology of semiconductor industry,lithography technology is facing the difficulties of technical complexity and greatly increased cost caused by diffraction limit.As a high-yield and high-precision patterning process,nanoimprint lithography?NIL?is considered to be one of the most promising nanopatterning techniques to overcome the diffraction limit of lithography technology.However,the current NIL focuses only on the definition of photoresist pattern.The preparation of optoelectronic devices involves many complex processes including deposition of functional materials,polymer patterning,etching and so on.These cumbersome steps have brought many shortcomings for the subsequent device preparation:waste of materials,long preparation time and narrow selection range of substrate materials caused by chemical etching,which limit the practical application of NIL.In order to solve these problems,our work utilized NIL to directly patternize different functional materials and directly prepare optoelectronic devices on different substrates,which greatly shortens the preparation time and reduces the production cost of devices.The main achievements are as follows:?1?Stable polarization-sensitive photodetector based on two-dimensional perovskite.Through the traditional NIL method,the crystallization process of quasi two-dimensional layered Ruddlesden-Popper perovskite is limited in the micro-channel between PDMS template and substrate,and highly-aligned micro wire crystal arrays with high crystal quality and uniform morphology are obtained.Based on these high-quality micro-wire crystal arrays,we have achieved a high-performance photodetector with a Responsivity up to 3.5 AW^-1,a Detectivity as high as 10¹⁵ Jones and a response time as low as 4.1 ms?for rise?and 3.3 ms?for decay?.Due to the anisotropic structure of the micro-wire arrays and the stability of the two-dimensional perovskite itself,the photodetector not only is polarization-sensitive,but also possesses excellent stability.It still maintains its initial performance after being stored in the environment with relative humidity up to 60%for 6 days.?2?Perovskite nanowire array photodetectors with high performance stability.Nanowire arrays with long period stability were prepared by edge adsorption effect assisted NIL method.First of all,in the process of NIL,the hydrophobic layer on the template is transferred to the surface of perovskite micro/nanowire crystals,forming an in-situ encapsulation layer to isolate water and oxygen in the air,greatly improving the stability of perovskite micro/nanowire crystals.Secondly,because the perovskite micro/nano crystal prepared by this method has high crystal quality,there are few defects in the crystal,which further improves the long-term stability of micro nanowires.In addition,the highly ordered microwire arrays enhances the hydrophobicity.Based on these three reasons,the photodetector based on this micro/nanowire array not only has high performance with a response of up to 20 AW^-1,but also long-term stability.Even after one year of exposure in the air,the device still maintains 96%of initial performance.?3?shape-desinable and size-conrtolable micro-ring resonator arrays with design and adjustable size.By the edge adsorption assisted NIL,a micro-ring resonator arrays with designable shape and adjustable size were prepared.During the crystallization process of perovskite precursor solution,nucleation and crystallization take place at the interfaces of the micro-pillars and the substrate,and finally micro-ring crystal arrays with the same perimeter as the micro-pillar are formed on the substrate.By changing the shape and size of the template,the micro-ring resonators with different shapes and sizes are obtained.By changing the shapes of the template micro-pillar arrays,different shapes of micro-ring resonators such as triangles,squares,pentagons,hexagons and pentagrams were prepared.By changing the sizes of the template micro-pillar arrays,micro-ring resonators with different diameters were obtained.Pumped by a femtosecond laser of 400 nm,the microring shows obvious characteristics of laser emission,which proves the high performance of the microring resonator.?4?Pressure sensor based on gold nanoparticle densely packed micro/nanowires.By the NIL method,gold nanoparticles can be self-assembled into a densely packed micro/nanowire structure.Based on this kind of micro/nanowire,a high performance pressure sensor was fabricated.This kind of pressure sensor has a large number of conductive nanoparticles to provide contact points,and even weak pressure can cause great changes in conductivity,so the detection limit is as low as 25Pa.The pressure sensor can monitor the movement of human body in real time,such as grasping action,fingers and wrist bending,vocal cord vibration and pulse signals of different parts of human body.Even the pulse waveform of a pregnant women can be distinguished.