Jean-Luc Muraro

Reliability modeling of capacitive RF MEMS

The kinetic of dielectric charging in capacitive RF microelectromechanical systems (RF MEMS) is investigated using an original method of stress and monitoring. This effect is investigated through a new parameter: the shift rate of the actuation voltages. We demonstrate that this lifetime parameter has to be considered as a function of the applied voltage normalized by the contact quality between the bridge and the dielectric. We also demonstrate that this phenomenon is related to Frenkel-Poole conduction, which takes place into the dielectric. We finally propose a model that describes the dielectric charging kinetic in capacitive RF MEMS. This model is used to extract a figure-of-merit of capacitive switches lifetime.

Investigation of dielectric degradation of microwave capacitive microswitches

This paper reports on the investigation of stiction and screening effects, which principally limit the lifetime of capacitive RF MEMS. These phenomena are the consequence of the dielectric charging which occurs during the running of the switch. To understand this effect, we have developed a specific test set which measures the microwave and electromechanic performances to evaluate the reliability of RF MEMS. Several experiments have thus been performed such as DC bias stress and cycling. These tests have shown that the dielectric charging creates a drift of the threshold voltages and that the difference between the pull-down and the pull-up voltages is an important parameter which drives the type of failure: stiction or screening.

GaN for space application: almost ready for flight

On the last years, gallium nitride (GaN) technology has made a remarked breakthrough in the world of microwave electronics. Power transistors are now available. How this GaN technology would impact space-borne units is now a priority concern. Although the power capability of GaN technology is the first obvious profit, GaN could also be used for other applications like low noise amplifiers, mixers, and probably more. The high sustainable temperature of GaN transistors is most striking advantage for in-flight use. This is connected to packaging design which is also experiencing a lot of activities and quick progresses. Of course, space application is dependent upon the full demonstration of reliability and this constitutes another field of investigation. Finally, after 8 years of GaN studies, experimental results are presented: they open wide the road a revolution inside space-borne electronics: the rise of GaN.

New approach for an accurate Schottky Barrier Height's extraction by I-V-T measurements

This paper proposes a diagnostic tool dedicated to the analysis of the Schottky Barrier Height (SBH). The proposed method is mainly relevant for studying gate related failure mechanisms in electronic devices. In this case, the SBH of gallium nitride High Electron Mobility Transistors (HEMTs) is investigated in terms of mean SBHs value and dispersion. It is shown that according to given temperature and gate current ranges, linear relationships can be extracted between the mean SBH and the inhomogeneities that appear in forward-biased diode. These behaviors are able to highlight different kind of defects, revealing possible weaknesses of the devices.

Trap characterization of AlGaN/GaN HEMTs through drain current measurements under pulsed-RF large-signal excitation

An advanced microwave characterization technique has been developed to determine the trapping and detrapping time constants due to wide Pulsed-RF large-signal excitation of AlGaN/GaN High-Electron Mobility Transistors (HEMTs). This approach is based on combined Continuous Waveform (CW) Time-Domain Load-Pull measurements and low frequency (LF) drain current transient measurements under one wide non-periodic Pulsed-RF excitation to investigate trapping phenomena. The trap capture and emission time constants are extracted by applying the current-transient method for different RF large-signal input power levels and for varying duration of pulse-width (PW) of the one pulse-RF excitation. The strong influence of the RF load-line excursion in the Drain current collapse after the RF stimulus is also demonstrated.

Specific Characterization for Destructive Single Event Effects on GaAs Power P-HEMT MMIC

Specific Single Event Effects characterization based on RF and worst case DC conditions are used to demonstrate that two European GaAs power P-HEMT MMIC processes are safe under heavy ions.

Characterization of Defects in AlGaN/GaN HEMTs Based on Nonlinear Microwave Current Transient Spectroscopy

This paper presents a new nonlinear microwave-based characterization methodology for the study of the deep levels proprieties in gallium nitride (GaN)-based high electron mobility transistors (HEMTs). Currently, it is unique measurement method allowing the extraction of time constants of HEMTs operating under large signal RF conditions. This method improves the conventional dc techniques, since it employs RF excitation during the filling condition to investigate the impact of “real-life” RF excitation on the trapping mechanisms. The experimental results demonstrate that, beyond the presence of Poole–Frenkel effect, the slow detrapping time constant is accelerated by the power dissipation of the trapping bias point. Moreover, it is possible to distinguish the impact of dc and RF conditions on the trapping phenomena. The temperature measurements allow identifying the 0.75-eV deep level, attributed to extended defects in GaN, when ionized under dc excitation. This deep level trap is probably located in the buffer layer and contributes to the RF trapping phenomenon.

Safe operating area of GaAs MESFET for nonlinear applications

This paper provides a new approach to evaluate the transistor safe operating area for a nonlinear operation in the overdrive operating conditions. This approach has been implemented for a MESFET technology. The methodology consists in performing ON-state and OFF-state accelerated DC step stresses for bias conditions, which can be reached by VDS and VGS sweeps in the overdrive operating conditions. Hence, the results of an RF ageing test performed in nonlinear conditions have confirmed the methodology used in this paper