Suppressed charge trapping characteristics of (NH₄)₂Sx passivated GaN MOS device with atomic layer deposited HfAlOx gate dielectric

Abstract

The charge trapping behaviors of ammonium poly-sulfide,(NH4)(2)S-x.,passivated GaN MOS device with atomic layer deposited HfAlOx. gate dielectric and DC-sputtered TiN gate electrode are investigated and compared with those of GaN MOS device with hydrochloric acid, HCI, passivation. Compared to non-S passivated device, higher peak capacitance (>20% @1 MHz), reduced frequency dispersion (similar to 30% down arrow) lower hysteresis (similar to 34% down arrow), higher breakdown (1.3x), lower stress induced flat-band voltage (V-FB) shift (similar to 30% down arrow), and lower interface state density (D-it) stronger immunity D-it generation (Delta D-it) against gate bias voltage are attained with S-passivated device. Further improved characteristics are observed with post deposition annealing at 400 degrees C for 10 min. These behaviors are mainly attributed to higher bond strength energy of S-O and S-N than those of CI-O and Cl-N bonds.