Proposal and simulated results of a normally off AlGaN/GaN HFET structure with a charged floating gate

A normally off AlGaN/GaN Hetero‐junction Field Effect Transistor (HFET) structure is proposed. Two dimensional electron gas (2DEG) of more than 1 × 1013 cm–2, which a AlGaN/GaN HFET generally has, can be compensated completely by the negative charge in a floating gate or in a SiO2 layer on the AlGaN. Computer simulation showed that the threshold voltage was shifted from ‐3 V to ‐15 V with 20 nm SiO2 layer between the control gate and the AlGaN layer, but it was also shifted to +5V with 5 × 1013 cm–2 electrons (negative charge) in the middle of the SiO2 layer (a floating gate) or minus ions in the SiO2 layer itself. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)