Growth And Buffer Layer Research Of Nitride Semiconductor On Graphene

The widely-studied GaN and AlN belonging to Ⅲ-nitrides semiconductor material own excellent photoelectric properties and wide adjustable band gaps,which have great advantages and bright prospects in the fields of lighting,display,high frequency and high power electronic devices,optical storage,communication and energy etc.It is generally accepted that the performance of semiconductor device is affected by the wafer.Until now,GaN and AlN wafer have been mainly synthesized by heteroepitaxy on sapphire.Lattice mismatch and thermal mismatch between epitaxial layers and substrates are still the key factors that limit the crystal quality.In recent years,the discovery of graphene and it’s used as substrates for crystal growth have provided a new train of thought and method for epitaxy of GaN and AlN.Due to the lack of dangling bond on graphene surface,epitaxial layers and graphene are combined by weak van der Waals force,which may help improving the crystal quality by overcoming lattice mismatch and realizing easy exfoliation of epilayers.Moreover,flexible devices will be obtained by growing microstructures of GaN and AlN on graphene,which can facilitate their generalization in foldable and wearable applications.In this works,we drew on the experience of proven two-steps growth method to carry out our research about GaN and AlN grown on graphene,where low temperature growth of buffer layers was followed by high temperature growth of epilayers.Good buffer layer can improve the crystal quality and guarantee the normal function of device structure,in which buffer layers provide nucleation sites for epitaxial process.So,it is necessary to study the whole growth process of GaN and AlN on graphene systematically,especially,the stage of growth of buffer layers.Graphene/Si C was used as the preferred substrate.The as-grown GaN and AlN have been characterized by scanning electron microscopy(SEM),Raman spectra,photoluminescence(PL),transmission electron microscope(TEM),and X-ray diffraction(XRD)etc.Graphene grown by plasma-enhanced chemical vapor deposition(PECVD)was also tentatively utilized as substrate for epitaxy of GaN and AlN.Finally,we offered a feasible method to fabricate self-organized phosphor-free multiband-emitting GaN based LED on graphene.Principle of multiband emitting and structural characteristics of LED are also demonstrated.