Al2O3 Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers

An Al2O3 insulated-gate (IG) structure was utilized for controlling the surface potential and suppressing the gate leakage in Al0.2Ga0.8N/GaN heterostructure field effect transistors (HFETs) having thin AlGaN barrier layers (less than 10 nm). In comparison with Schottky-gate devices, the Al2O3 IG device showed successful gate control of drain current up to VGS= +4 V without leakage problems. The threshold voltage in the Al2O3 IG HFET was about -0.3 V, resulting in the quasi-normally-off mode operation

DC and microwave performance of AlGaN/GaN HEMTs passivated with sputtered SiNx

The effects of sputtered and room temperature plasma enhanced chemical vapour deposition (RT-PECVD) SiNx passivation on the dc and microwave performance of AlGaN/GaN high electron mobility transistors (HEMTs)are studied. The pulsed I–V characteristics from a class B quiescent bias point and transient measurements indicate that the sputtered SiNx passivation is more efficient in suppressing lag effects in AlGaN/GaN HEMTs. Dispersion-free sputtered SiNx passivated AlGaN/GaN HEMTs were obtained using this technique. Continuous-wave (CW) measurements without active cooling give a maximum output power density of 6.6 W mm−1 at Vgs=−4 V, Vds = 50 V and a maximum power added efficiency of 51.3% at Vgs=−4 V, Vds = 30 V at 3 GHz on 2 7 50 μmAlGaN/GaN HEMTs on the sapphire substrate, with a gate length of 2 μm and without field-plated gates. To the best of our knowledge, this is the highest level power density reported on the sapphire substrate without field-plate design. The extrinsic cut-off frequency ( ft) and maximumoscillation frequency ( fmax) are 51 GHz and 100 GHz, respectively, on 2 7 50 7 0.15 μm HEMTs. To our knowledge, the sputtered SiNx passivation for AlGaN/GaN HEMTs is a unique technique, which has never beenpublished before

DC and microwave performance of AlGaN/GaN HEMTs passivated with sputtered SiNx

The effects of sputtered and room temperature plasma enhanced chemical vapour deposition (RT-PECVD) SiNx passivation on the dc and microwave performance of AlGaN/GaN high electron mobility transistors (HEMTs)are studied. The pulsed I–V characteristics from a class B quiescent bias point and transient measurements indicate that the sputtered SiNx passivation is more efficient in suppressing lag effects in AlGaN/GaN HEMTs. Dispersion-free sputtered SiNx passivated AlGaN/GaN HEMTs were obtained using this technique. Continuous-wave (CW) measurements without active cooling give a maximum output power density of 6.6 W mm−1 at Vgs=−4 V, Vds = 50 V and a maximum power added efficiency of 51.3% at Vgs=−4 V, Vds = 30 V at 3 GHz on 2 7 50 μmAlGaN/GaN HEMTs on the sapphire substrate, with a gate length of 2 μm and without field-plated gates. To the best of our knowledge, this is the highest level power density reported on the sapphire substrate without field-plate design. The extrinsic cut-off frequency ( ft) and maximumoscillation frequency ( fmax) are 51 GHz and 100 GHz, respectively, on 2 7 50 7 0.15 μm HEMTs. To our knowledge, the sputtered SiNx passivation for AlGaN/GaN HEMTs is a unique technique, which has never beenpublished before

Oxygen Ion Implantation Isolation Planar Process for AlGaN/GaN HEMTs

A multienergy oxygen ion implantation process wasdemonstrated to be compatible with the processing of highpower microwave AlGaN/GaN high electron mobility transistors (HEMTs). HEMTs that are isolated by this process exhibited gate-lag- and drain-lag-free operation. A maximum output power density of 5.3 W/mm at Vgs = −4 V and Vds = 50 V and a maximum power added efficiency of 51.5% at Vgs = −4 V and Vds = 30 V at 3 GHz were demonstrated on HEMTs withoutfield plates on sapphire substrate. This isolation process results in planar HEMTs, circumventing potential problems with enhancedgate leakage due to the gate contacting the 2-D electron gas at themesa sidewall