High-quality oxide/nitride/oxide gate insulator for GaN MIS structures

Abstract

We report on a SiO/sub 2//Si/sub 3/N/sub 4//SiO/sub 2/ (ONO) gate insulator stack deposited on GaN by jet vapor deposition (JVD) technique. Capacitors fabricated using the JVD-ONO on GaN are characterized from room temperature to 450/spl deg/C using capacitance-voltage (C-V), current-voltage (I-V), AC conductance, and constant-current stress measurements. We find excellent operating characteristics over the measured range, most notably: (1) very low leakage current, (2) extremely high hard-breakdown strength, (3) low interface-trap density, and (4) low net dielectric-charge density. Moreover these performance figures remain well within acceptable limits even for operating temperatures as high as 150/spl deg/C. In addition, we measure both the capture cross-section of the interface traps and the surface-potential fluctuation at the GaN/ONO interface. All results suggest that JVD-ONO is an excellent choice for a gate dielectric in GaN-based MISFETs.