This paper shows the possibility to improve DC and RF electrical performances of AlGaAs/InGaAs PHEMTs by using low gamma radiation dose. The drain–source saturation current and the DC transconductance increase when the devices are irradiated with a gamma dose of 42.8krad(GaAs) and then remain constant up to 0.85Mrad(GaAs). This improvement is attributed to a reduction of access resistances. In the same time, the Schottky diode and the current-gain cut-off frequency of these components are not degraded by the gamma irradiation. Moreover, the maximum output power density is improved by 18%. This paper demonstrates that it is possible to improve the component electrical performances by using an original method.

In this paper, the possibility to achieve output power density exceeding 10 W/mm at 2 GHz using 1 mm gate width GaN HEMTs on 4” large diameter Si (111) substrate is demonstrated for the first time. Additionally, storage tests at 325°C reveal the high thermal stability of these devices which we attribute to the in-situ grown SiN cap layer. These data are a first step towards a cost-effective high RF power density for high reliability GaN-on-Si HEMT technology.

An original method is presented to improve DC electrical performance of AlGaAs/InGaAs PHEMTs by using a low neutron radiation dose. An increase of the drain-source saturation current, a decrease of the knee voltage and a reduction of the leakage current of the Schottky contact are observed without degrading the current-gain cutoff frequency when the devices are irradiated with a neutron radiation dose of 1.2 x 10(10) neutrons/cm(2).

Low microwave noise performance of AlGaN/GaN HEMTs fabricated on MOCVD epitaxial structures grown on composite substrates (SiCopSiC) is reported. They are made of a thin SiC single-crystal layer transferred on top of a thick polycrystalline SiC wafer. The transistor fabrication process is similar to the one developed for AlGaN/GaN devices on SiC substrate. A minimum noise figure of 0.12 dB with an associated gain of 14.8 dB at 3 GHz is found, showing the capability of gallium-nitride based devices for low noise microwave applications in the S-band.

This paper describes the research activity that is being carried out in the MOCHA project, a cooperative R&D effort at the European scale. The aim of the project is to develop reliable modelling and simulation solutions for SiP design verification.

AlInN/AlN/GaN based HEMTs were fabricated on SiC substrate to demonstrate the high potentiality of these heterostructures. The presented results confirm the high performances reachable by AlInN based technology with an output power of 6.8 W/mm at 10 GHz with a gate length of 0.25 mu m. A good extrinsic transconductance value of 400 mS/mm was also measured on these transistors. The results are believed to be the best power results published about AlInN/GaN HEMTs.

DC‐ and RF‐pulsed measurements of AlGaN/GaN HEMTs on high resistive silicon (111) substrate are achieved under probes in the 300–525 K temperature range. Current collapse and heating effects are studied and it demonstrates the high temperature properties of these devices. Hence the potential of this technology for power applications at microwave frequencies is confirmed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2301–2305, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21897

The present invention relates to a coaxial stub characterized in that it comprises two probes ( "slugs") and presents a lateral translational movement along the axis Ox.Le principle of dual tuner slugs is based on the displacement of the two ends of different characteristic impedance line 50 Omega within a closed part of cylinder and the other by standard connectors.

AlGaN/GaN HEMTs are realized on a sapphire substrate without a field plate, for power applications at microwave-frequencies using a new Ar+ ions implant-isolation technology. The first results obtained are veri v good in terms of device isolation. (c) 2005 Wiley Periodicals, Inc.

The benefit of high drain-source bias voltages of GaN devices on sapphire substrates for high linearity applications is demonstrated. Whatever the output power densities considered, the corresponding intermodulation ratio is at least 20 dB better than usual PHEMT devices on GaAs substrates for the same power density. This study demonstrates that GaN devices are ideal candidates for applications requiring high power and high linearity behaviours simultaneously.

The authors report on the effects of plasma pre-treatment before SiNx passivation on the electrical traps of undoped AlGaN/GaN HFETs. Different plasmas were tested with O2 or CF4 or (O2+CF4) gas. The maximum drain current decreased when an O2 plasma was used before SiNx passivation, and increased up to 35% in the other cases. The best results were obtained using an (O2+CF4) plasma. In that case, an important decrease of the knee voltage was observed in the Ids(Vds,Vgs) characteristic which becomes independent of the bias variation. The influence of the lighting on the electrical characteristics of AlGaN/GaN HFETs was also studied. We have deduced that a part of the electrical traps is located at the surface of the structure and that another part is present under the gate, in the volume of the AlGaN layer, and/or at the interface AlGaN/GaN.

The advantage of planar technology for the AlGaN/GaN HEMTs realization is demonstrated in this paper. A breakdown voltage closed to 100 V and an output power density of 4 W/mm at 4 GHz have been measured on a 2x25x1.5 μm2 HEMT on sapphire substrate. These results are very promising because the devices have not been passivated, and no T gate has been achieved. Moreover, planar technology offers the advantage of a better reliability. At present time, it is the best power result obtained with an isolation by argon implantation.

The advantage of planar technology for the AlGaN/GaN HEMTs realization is demonstrated in this paper. A breakdown voltage closed to 100 V and an output power density of 4 W/mm at 4 GHz have been measured on a 2x25x1.5 µm² HEMT on sapphire substrate. These results are very promising because the devices have not been passivated, and no T gate has been achieved. Moreover, planar technology offers the advantage of a better reliability. At present time, it is the best power result obtained with an isolation by argon implantation.

The high potential at microwave frequencies of AlGaN/GaN high electron mobility transistors (HEMTs) on high resistive silicon (111) substrate for power applications has been demonstrated in this letter. For the first time, an output power density close to 1.8 W/mm and an associated power added efficiency of 32% have been measured on a 2 x 50 x 0.5 mum(2) HEMT with a linear power gain of 16 dB. These results constitute the state of the art.