High Performance Metal-Gate/High-kappa GaN MOSFET With Good Reliability for Both Logic and Power Applications

Abstract

The gate-recessed GaN MOSFET on a Si substrate is demonstrated to achieve a record highest normalized transistor current (mu C-ox) of 335 mu A/V-2 (410 mA/mm at L-G = 5 mu m and only V-G = 4 V), I-ON/I-OFF of 9 orders of magnitude, small 79 mV/dec sub-threshold slope, a low oxide/GaN interface trap density of 1.2 x 10(10) eV(-1)/cm(2), a low on-resistance of 17.0 Omega-mm, a high breakdown voltage of 720-970 V, and excellent reliability of only 40 mV Delta V-T after 175 degrees C 1000 s stress at maximum drive current. Such excellent device integrities are due to the high-kappa gate dielectric and the high conduction band offset (Delta E-C) of SiO2/GaN. From the calculation results of self-consistent Schrodinger and Poisson equations, the good reliability of GaN MOSFET is related to the confined carrier density within the GaN channel, which is in sharp contrast to the strong wave-function penetration into the high-trap density AlGaN barrier in the AlGaN/GaN HEMT.