Fabrication and characterization of N-face AlGaN/GaN/AlGaN HEMTs

Abstract

The paper reports on the characteristics of N-face AlGaN/GaN/AlGaN HEMTs. Ohmic contact optmization experiments based on the Ti/Al/Ni/Au metallization scheme commonly used for Ga-face AlGaN/GaN HEMTs were carried out and a low contact resistance of 1.3 Ohm/mm was achieved. The devices were then characterized before and after SiN passivation. Before passivation, large current dispersion was observed in 80mus pulsed I-V measurements compare to the DC I-V curves. The adoption of a SiN passivation layer improved the I-V pulsed characteristics at 80mus but current dispersion was still severe when using shorter (200ns) pulse widths