Growth of GaN by Vacuum Thermal Evaporation on Flexible Graphene/PET Substrates

The formation of GaN/graphene hybrid films through the vacuum thermal evaporation of GaN on a double layer flexible substrate consisting of a graphene layer on PET, has been studied. The thicknesses of the GaN layers and, therefore, the structure and properties of the hybrid films, were critically influenced by the deposition time. The structure of the GaN layer on graphene was amorphous, according to small angle X-ray diffraction spectra. The existence of the GaN layer on top of the graphene and the absence of a N–C covalent bond at the interface of the GaN/graphene hybrid film was confirmed by using Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The free π-electrons of graphene took the conductive role in the hybrid films. A slight change in electrical properties was observed with increasing thickness of the GaN layer, due to the shunt resistance between this layer and the graphene layer. The grain size of the GaN films increased and transmittance within the visible range decreased with increasing deposition time, i.e., increasing thickness. The method presented demonstrates the feasibility of realizing transparent conductive GaN/graphene hybrid films on flexible PET, which are in high demand for fabricating optoelectronic and sensing devices.