High-performance GaN/InGaN heterostructure FETs on Mg-doped GaN current blocking layers

Abstract

Nitride-based GaN/In 0.12Ga 0.88N heterostructure field effect transistors (HFETs) with semi-insulating Mg-doped GaN current blocking layers were successfully fabricated. The as-grown layers exhibited a very smooth surface. The DC characteristics of these HFETs were substantially improved over those previously reported. Devices with a 0.75 μm gate length showed a maximum drain current ( I DS) of 421 mA/mm, and a maximum g m of about 85.6 mS/mm at V GS between −0.5 and −3 V. The device which had a very good pinch-off with source–drain (S–D) leakage current was negligibly small, in the range of 10 −1–10 −2 mA/mm. The RF characteristic of devices showed the current gain cutoff frequency, f T, was 7.45 GHz and the maximum oscillation frequency, f MAX, was 12.36 GHz.