High transconductance AlGaN/GaN-HEMT with recessed gate on sapphire substrate

Recessed gate AlGaN/GaN high electron mobility transistors (HEMTs) grown on sapphire substrate have been fabricated. In order to improve FET performances, we optimized the layer structure and the electrode arrangement of the HEMT, and hence 0.15 mum gate-length AlGaN/GaN-HEMTs with recessed gate were successfully fabricated and the obtained transconductance was as high as 450 mS/mm. In this paper we describe the improvement of HEMT layer structures on sapphire substrate, the optimisation of an offset arrangement of gate electrodes, and the results of DC/RF measurements of our HEMTs. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.