Schematic diagram of the inductively heated sublimation reactor. Tt and Tb refer to the top and bottom crucible temperatures, respectively.
The effect of temperature on AlN growth observed in three samples: a) SEM image of the hexagonal features grown at TG=1820-1830°C, EDX of these features (AlNxSiCy ); b) AlN single crystal growth at TG=1870-1880°C; cracks due to thermal and mechanical stresses are evident; c) colorless and transparent AlN islands with flat c-faces grown at TG=1920-1930°C.
The effect of growth time on AlN crystal morphology at TG=1930°C and a source-to-seed distance of 10 mm. Left: AlN single crystal, 200-300 mm2 large and 300-350 µm thick, after 15 hours of growth; Right: AlN single crystal, 200-300 mm2 large and 650-700 µm thick, after 28 hours of growth.
Growth steps on the c-plane observed by an optical microscope.
SEM image of a cleaved cross-section of an AlN crystal (left) and XRD analysis (right).