Fabrication and Characterization of Gate-Last Self-Aligned AlN/GaN MISHEMTs With In Situ SiN_x Gate Dielectric

摘要

This paper reports on the fabrication and characterization of gate-last self-aligned SiN/AlN/GaN MISHEMTs. The devices featured grown SiN by metal–organic chemical vapor deposition as a gate dielectric and for surface passivation. Selective source/drain regrowth was incorporated to reduce contact resistance. SiN sidewall spacers and low- benzocyclobutene polymer () supporting layers were employed under the gate head to minimize the parasitic capacitance for high-frequency operation. The device with a gate length ( of exhibited a maximum drain current density ( exceeding 1600 mA/mm with a high ON/OFF ratio ( of over . The current gain cutoff frequency ( and maximum oscillation frequency ( were 55 and 86 GHz, respectively. In addition, the effect of temperature, from room temperature up to 550 K, on the dc and RF performances of the gate-last self-aligned MISHEMTs was studied.