Fig. 1. (Color online) (a) AlN single crystal. (b) AlN samples. (c) R_a of AlN sample at area of 10 × 10 μm².

Fig. 2. (Color online) Raman spectrum of AlN samples. (a) Wavelength from 100 to 1000 nm. (b) Detailed E₂ (high) phone mode peaks.

Fig. 3. (Color online) HRXRD of AlN samples (a) (0002) plane and (b) ( ) plane.

Fig. 4. (Color online) Schematic diagrams of AlN single crystal grown on Si-polar SiC seed. (a) SiC macroscopic steps and deposited AlN 3D islands. (b) AlN 3D islands lateral overgrowth and dislocation formation. (c, d) Cavity movement and dislocation "annihilation".

Fig. 5. SEM images of AlN samples etched in KOH/NaOH melt solution at 320 °C for 3 min. (a) Sample I. (b) Sample II. (c) Sample III.