Effective Passivation With High-Density Positive Fixed Charges for GaN MIS-HEMTs

Abstract

An effective passivation with high-density positive fixed charges was demonstrated on GaN MIS-HEMTs. The positive fixed charges at the interface between passivation and AlGaN surface can reduce the surface potential and expand the quantum well under Fermi level. Besides, to satisfy charge balance, the net charge density at the AlGaN surface must equal to the 2DEG carrier density. Thus, the positive fixed charges passivation can increase the 2DEG carrier density and improve the switching performance of GaN MIS-HEMTs. In this paper, we demonstrated a high-density positive fixed charges $(\sim 2.71 \times 10^{13} e/cm^{-2})$ passivation using SiON for GaN MIS-HEMTs. The device with SiON passivation exhibits significant improvements in $I$ – $V$ characteristics and dynamic RON compared to the conventional SiN passivated device.