Study Of Structure Design And Light-emitting Device Based On ZnO/graphene/p-GaN Heterostructure

In recent years,people's demand for high-brightness,miniaturized,energy-saving and environmentally-friendly LEDs has continuously increased,showing great application potential in the field of display lighting and the like.Among many LED devices,LED devices represented by GaN blue-violet light are relatively mature and widely used.However,its disadvantages such as high production cost and complicated manufacturing process limit the further development of deviceization.With the rapid development of the semiconductor industry,zinc oxide(ZnO),another representative material of the third generation semiconductor,is considered to be an ideal material for constructing ultraviolet light emitting/laser diodes.At room temperature,ZnO has a wide direct band gap(3.37 e V),a strong exciton binding energy(?60 me V),and has the characteristics of low preparation cost and environmental friendliness,caused a wave of research.Since the first two-dimensional layered graphene material was obtained by mechanical peeling in 2004,it has received considerable attention in the scientific and engineering communities.The material has excellent photoelectric properties and good chemical and mechanical stability.Due to the resonance behavior of ? electrons and ?+? electrons in its Dirac cone energy band structure,graphene exhibits surface plasmon(SP)resonance effects,an interesting physical phenomenon that has greatly promoted the development of related research.Especially in the aspect of graphene surface plasmon to improve the luminous efficiency of LED devices,researchers have gradually carried out related work and obtained some experimental phenomena of improved luminescence.In this paper,in view of the difficulty of p-type doping of ZnO materials,constructing n-ZnO / p-GaN heterojunction LEDs,the graphene SP is re-structured,and the growth method and growth conditions are gradually optimized to achieve efficient and stable heterostructure Ultraviolet luminescence and controlled growth of ZnO nanowires(NWs)on the graphene layer.The specific work and main conclusions are as follows:Wet transfer graphene,covering a single layer of graphene on the surface of pGaN,using magnetron sputtering,pulsed laser deposition(PLD),atomic layer deposition(ALD)to construct n-ZnO film/Graphene/p-GaN structure,analyze the luminescence properties of the devices made by the three preparation methods.Compared with the original n-ZnO/p-GaN structure,it is found that the ZnO film prepared by the atomic layer deposition method has a significant improvement in the luminous intensity of the device.The one-dimensional ZnO nanostructure was introduced into the device,and by optimizing the processing conditions of the graphene layer,the controlled growth of ZnO nanowires on the graphene was achieved.Oxygen plasma-treated graphene layer is used in ZnO nanowire/p-GaN LED to generate SP effect.Compared to the original n-ZnO / p-GaN junction device,the graphene-modified heterojunction shows a ZnO ultraviolet(UV)electroluminescence(EL)intensity increase of about 4 times.Timeresolved spectroscopy and temperature-dependent luminescence measurements indicate that EL enhancement is due to the coupling of ZnO excitons and graphene SP.The current research not only provides an opportunity to construct a three-dimensional heterostructure from a one-dimensional nanorod vertical array and a two-dimensional graphene layer,but also provides an effective strategy to improve the luminous efficiency of other types of devices.