Research On Graphene-based Ultraviolet Light Trapping Structures

As the most fascinating 2D material,graphene has received great attention in photonic research from ultraviolet to terahertz ranges and has boosted the development of advanced optics from nano-optics to angstrom-optics.Graphene is a two-dimensional crystal with a single atom thickness composed of planar carbon atoms arranged in a honeycomb order.Graphene has a unique zero band gap electron energy band structure,which led it has excellent performance in mechanics,electricity and optics.These excellent properties make graphene have a broad prospect in the application of optoelectronic devices.The absorption of incident light energy plays an important role in optical detectors and optoelectronic devices,and with the method of preparing high quality graphene,researchers can explore its optical trapping ability and apply it to photoelectron technology based on the excellent photoelectric properties of graphene.In the visible and infrared wavelengths,many of the trapping structures based on graphene have been proposed,and these structures based on graphene have many advantages over other trapping structures.However,there are few studies have extended the application of graphene to the ultraviolet band,but in this band,the research on the structure of graphene is very promising in the field of ultraviolet detection,ultraviolet photoluminescence,Raman microscopy,chemical sensing,flame monitoring and space communication.A high performance ultraviolet photoelectric device can be developed based on the graphene trap structure.In addition,due to the many-body effect of graphene in the ultraviolet band,there is a stronger interaction with incident light in the ultraviolet band than in the visible and infrared bands,the absorption rate of normal incident ultraviolet light is higher than that of other bands,but it is still not more than 10%,which limits the development of the graphene photoelectric device in this band.Based on the above problems,this dissertation studies the UV-band trapping structure based on graphene to enhance the interaction between graphene and light,so as to improve the absorption of graphene to ultraviolet light,which lays the foundation for designing high performance ultraviolet optoelectronic devices.In this paper,three different types of trapping structres based on graphene are studied.The first one is to enhance the ultraviolet absorption of graphene by using the metal plasmonics,and the absorption rate of graphene can be increased to 43%.The structure has no angle dependence and is easy to be integrated into optoelectronic devices.The second is a unpatterned graphene ultraviolet trapping structure,which eliminates the need to construct a nano-patterned array on the graphene surface,greatly reducing the processing difficulty and increasing the single graphene absorption rate to 71.4%.The third is a complete dielectric nano-optical absorber based on graphene,all parts of the structure use a lossy medium,which will greatly reduce the energy dissipation in other materials,so that the absorption rate of graphene is greatly increased and can be increased to more than 99%.