Capacitance-voltage characterization of AlN/GaN metal-insulator-semiconductor structures grown on sapphire substrate by metalorganic chemical vapor deposition

Electrical characterization of AlN/GaN interfaces was carried out by the capacitance-voltage (C-V) technique in materials grown by metalorganic chemical vapor deposition. The high-frequency C-V characteristics showed clear deep-depletion behavior at room temperature, and the doping density derived from the slope of 1/C² plots under the deep depletion condition agreed well with the growth design parameters. A low value of interface state density D_it of 1 × 10¹¹ cm^-2eV^-1 or less around the energy position of E_c-0.8 eV was demonstrated, in agreement with an average D_it value estimated from photoassisted C-V characteristics.