Study On Growth,Defects And Ultraviolet Detection Of GaN Films On Graphene

Gallium nitride(GaN),a wide band gap semiconductor material with many excellent photoelectric properties and stability,is suitable for optoelectronic devices and high power devices,which have bright prospects in the fields of lighting,display,fifth generation(5G)wireless communication,pilotless driving and national defense industry etc.At present,low-cost fabrication of high-quality GaN materials is the key to promote the development of GaN materials and devices.Due to the high cost of native GaN substrate,most of GaN-based devices are mainly synthesized on sapphire,silicon carbide(SiC)and silicon(Si)substrates by heteroepitaxy.However,the lattice mismatch and thermal mismatch between the substrate and the epitaxial layer by heteroepitaxy can significantly reduce the crystal quality,which is not conducive to the fabrication of subsequent devices.Graphene,a two-dimensional(2D)layered material with many fascinating properties,has been widely concerned.The growth of GaN films on graphene not only eliminates the lattice mismatch and improves the crystal quality of the films,but also allows the films to be released from graphene and easily transferred to other substrates.Therefore,it is of great significance to study the growth of GaN on graphene,which provides a new direction for the fabrication of GaN materials.This research offers a potential prospect for the development of GaN films in foldable and wearable applications in the future.In this work,ZnO was grown on graphene by atomic layer deposition(ALD).The growth characteristics of ZnO on SiC epitaxial graphene were studied.The growth of GaN was preliminarily carried out using ZnO as buffer layer.A transferable single-crystalline GaN films were synthesized on multilayer graphene(MLG)/SiC by the conventional two-step growth.The morphology and crystal quality of the film were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM),electron backscatter diffraction(EBSD),and X-ray diffraction(XRD)etc.Moreover,a GaN-based flexible ultraviolet(UV)prototype detector was fabricated and explored its photoelectric response characteristics.The microstructural defects of GaN films on graphene were investigated using both transmission electron microscope(TEM)and EBSD,including grain boundaries,stacking faults,and dislocations.This lays the foundation for exploring the growth of high quality GaN films on graphene.The threading dislocations of GaN were also investigated by two-photon excitation photoluminescence.