Flexible graphene-assisted van der Waals epitaxy growth of crack-free AlN epilayer on SiC by lattice engineering

Abstract Graphene has attracted much attention as novel buffer layer to grow III-nitrides. Here direct van der Waals epitaxy (vdWE) of high quality AlN films on graphene/SiC is demonstrated by effective lattice engineering and detailed nucleation mechanism is presented. The AlN films on graphene show high single crystalline quality, with the full width at half maximum (FWHM) of 79 arcsec for (1 0 2) asymmetry plane and 148 arcsec for (0 0 2) symmetry plane, respectively. First-principles calculations demonstrate the introduction of graphene enables the tunable lattice constant for the heteroepitaxy system and effectively releases the biaxial strains in AlN epilayers. The lattice engineering to minimize the strain of the epilayers is further confirmed by Raman spectra shift of graphene 2D peak. This provides a feasible way to grow high-quality AlN films with no cracks to meet the strict demands of devices, especially in ultraviolet optoelectronic devices.