Frequency dispersion of transconductance and output conductance in AlInN/GaN high electron mobility transistors is investigated in this paper. Broadband dispersion effects in the microwave frequency range are reported for the first time. A small-signal model is developed. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model is compared to experimental data for several bias conditions and different types of dispersion.

This paper presents an original characterization method of trapping phenomena in gallium nitride high electron mobility transistors (GaN HEMTs). This method is based on the frequency dispersion of the output-admittance that is characterized by low-frequency S-parameter measurements. As microwave performances of GaN HEMTs are significantly affected by trapping effects, trap characterization is essential for this power technology. The proposed measurement setup and the trap characterization method allow us to determine the activation energy Ea and the capture cross-section σnof the identified traps. Three original characterizations are presented here to investigate the particular effects of bias, ageing, and light, respectively. These measurements are illustrated through different technologies such as AlGaN/GaN and InAlN/GaN HEMTs with non-intentionally doped or carbon doped GaN buffer layers. The extracted trap signatures are intended to provide an efficient feedback to the technology developments

The surface chemistry of InAlN ultra-thin layers, having undergone an oxidation procedure usually running through the HEMT fabrication process (850 • C, O 2 and O 2 +Ar) is studied by XPS. The suitability of XPS analysis to operate as a retro-engineering tool for added value microelectronic devices fabrication is shown. A precise examination of the Al2p, In3d 5/2 , N1s, and O1s peaks directly informs about spatial and atomic arrangement. The formation of a covering 3 nm surface oxide is evidenced after O 2 annealing. Once annealed, two specific additional N1s contributions are shown, at higher (404.0 eV) and lower binding energies (397.4 eV) compared to the InAlN matrix one (396.5 eV). To our knowledge, such fingerprint is rather unusual for ternary III-V materials. It reveals the formation of a nitrogen deficient interlayer, situated between the oxide overlayer and the undisturbed matrix, and the presence of interstitial N 2 molecules trapped at the interface. After Ar annealing, both oxide and interface layers are partially reorganized. InAlN reactivity toward higher annealing temperature (950 • C) and its stability over time is finally discussed. N 2 molecules are unstable and progressively eliminated in time although nitrogen deficient interlayer still remains. Thermal treatments below 850 • C are recommended to preserve the barrier chemical integrity.

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A study of the electrical performances of AlInN/GaN High Electron Mobility Transistors (HEMTs) on SiC substrates is presented in this paper. Four different wafers with different technological and epitaxial processes were characterized. Thanks to intensive characterizations as pulsed-IV, [S]-parameters, and load-pull measurements from S to Ku bands, it is demonstrated here that AlInN/GaN HEMTs show excellent power performances and constitute a particularly interesting alternative to AlGaN/GaN HEMTs, especially for high-frequency applications beyond the X band. The measured transistors with 250 nm gate lengths from different wafers delivered in continuous wave (cw): 10.8 W/mm with 60% associated power added efficiency (PAE) at 3,5 GHz, 6.6 W/mm with 39% associated PAE at 10.24 GHz, and 4.2 W/mm with 43% associated PAE at 18 GHz.