AlGaN/AlN/GaN/SiC HEMT structure with high mobility GaN thin layer as channel grown by MOCVD

Abstract

Enhancement of the electrical properties in an AlGaN/GaN high electron mobility transistor (HEMT) structures was demonstrated by employing the combination of a high mobility GaN channel layer and an AlN interlayer. The structures were grown on 50 mm semi-insulating (SI) 6H-SiC substrates by metalorganic chemical vapor deposition (MOCVD). The room temperature (RT) two-dimensional electron gas (2DEG) mobility was as high as 2215 cm 2/V s, with a 2DEG concentration of 1.044×10 13 cm −2. The 50 mm HEMT wafer exhibited a low average sheet resistance of 251.0 Ω/square, with a resistance uniformity of 2.02%. The 0.35 μm gate length HEMT devices based on this material structure, exhibited a maximum drain current density of 1300 mA/mm, a maximum extrinsic transconductance of 314 mS/mm, a current gain cut-off frequency of 28 GHz and a maximum oscillation frequency of 60 GHz. The maximum output power density of 4.10 W/mm was achieved at 8 GHz, with a power gain of 6.13 dB and a power added efficiency (PAE) of 33.6%.