Achievement of polarity reversion from Al(Ga)-polar to N-polar for AlGaN film on AlN seeding layer grown by a novel flow‐modulation technology

N-polar AlGaN epi-layer was realized on AlN seeding layer grown with a novel flow-modulation method. The polarity reversion from Al(Ga)-polar to for AlGaN/AlN films confirmed by KOH etching and subsequent observation optical microscope as well high-resolution X-ray diffraction (HR-XRD) measurement. In particular, the dependence of crystalline quality defect size in epi-layers V/III ratio investigated HR-XRD scanning electron microscopy (SEM). It found that full width at half maximum (FWHM) value rocking curve (XRC) varied fluctuating mode N–polar epi-layers, FWHM small 450 arcsec achieved sample 988. Moreover, it revealed SEM measurement diagonal length hexagonal cone surface decreased sharply when 1236 used although morphology were not improved simultaneously. peculiar migration group-III atoms associated molar TMA/(TMA + TMG) considered be responsible this result.