Electrical Properties of Metal–Insulator–Semiconductor Capacitors on Freestanding GaN Substrate

The electrical properties of GaN metal–insulator–semiconductor (MIS) capacitors with as-grown SiO 2 , annealed SiO 2 , and SiN x insulators were investigated by capacitance–voltage ( C – V ), current–voltage ( I – V ), and time-dependent dielectric breakdown (TDDB) measurements. The MIS capacitor with the SiN x insulator was determined to have a lower interface trap density of 1×10 11 cm -2 eV -1 than the MIS capacitors with the as-grown and annealed SiO 2 insulators. In addition, the dielectric lifetime of the SiN x insulator was extrapolated to be more than 20 years at an even high voltage at room temperature. These results indicate that the high insulator/GaN interface quality and high reliability required for high-performance power devices can be achieved by the deposition of the SiN x insulator on GaN.