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.