Crystalline quality improvement of face-to-face annealed MOVPE-grown AlN on vicinal sapphire substrate with sputtered nucleation layer

•AlN templates with high crystalline qualities are fabricated on vicinal sapphires.•Fabrication processes are RF sputtering, MOVPE growth, and face-to-face annealing.•The concentrations of O, Si, and C impurities in the AlN template are low.•The surface of AlGaN grown on the AlN template is flat without large hillocks.