Influence comparison of N₂ and NH₃ nitrogen sources on AlN films grown by halide vapor phase epitaxy

A comparison of the nitrogen sources (N₂ and NH₃) influence on AlN films grown by high-temperature halide vapor phase epitaxy (HVPE) is reported. The x-ray rocking curves (XRCs) indicate that the full width at half maximum (FWHM) of (0002) plane for AlN films using N₂ as nitrogen source is generally smaller than that using NH₃. Optical microscope and atomic force microscope (AFM) results show that it is presently still more difficult to control the crack and surface morphology of AlN films with thicknesses of 5-10 μm using N₂ as the nitrogen source compared to that using NH₃. Compared with one-step growth, two-step growth strategy has been proved more effective in stress control and reducing the density of threading dislocations for AlN epilayers using N₂ as the nitrogen source. These investigations reveal that using N₂ as nitrogen source in HVPE growth of AlN is immature at present, but exhibits great potential.