Characterization of InN Grown Directly on Sapphire Substrate Using Plasma-Enhanced Metal Organic Chemical Vapor Deposition

Direct InN growth is demonstrated and characterized on a sapphire (Al₂O₃) substrate by plasma-enhanced metal–organic chemical vapor deposition using high-density nitrogen (N₂) microstrip-line microwave plasma. N₂ plasma irradiation at 650 °C for 20 min forms AlN on Al₂O₃ substrate. No peak regarding metallic In droplets is detected from InN/Al₂O₃ regardless of N₂ plasma irradiation. InN is found to be rotated 30° with their a-axis oriented to become $\left[10\overline{1}0\right]$ InN // $\left[11\overline{2}0\right]$ Al₂O₃. The transition layers are confirmed at the InN/Al₂O₃ interface regardless of N₂ plasma irradiation. The surface of InN consisted of large undulations with root mean square values >30 nm, suggesting that strain relaxation introduces misfit dislocations.