This work focuses on the early-life drift mechanisms in 150 nm AlGaN/GaN HEMTs on SiC under RF-HTOL stress at 9 GHz and 130 degrees C. Electrical measurements during the first hours of stress reveal significant shifts in threshold voltage, transconductance, and drain lag, indicating the activation of deep traps located in the buffer. A transient increase in gate leakage current is also observed under reverse gate bias, suggesting additional trapping or conduction paths at the AlGaN/SiN or cap/passivation interface. These electrical instabilities coincide with a progressive degradation of RF performance, notably in gain and power-added efficiency. Electroluminescence measurements further support the presence of electrically active defects, with distinct spatial patterns depending on the bias configuration.

For device qualification in harsh environments (space, avionic and nuclear), radiation testing identifies the sensitivity of the devices and technologies and allows to predict their degradation in these environments. In this paper, the analysis of the electrical characteristics and of the failure of a commercial SiC MOSFET after a Single Event Burnout (SEB) induced by proton irradiation are presented. The goal is to highlight the SEB degradation mechanism at the device and die levels. For failed devices, the current as a function of the drain-source bias (VDS) in off-state (VGS=0V) confirms the gate rupture. For the die analysis, Scanning Electron Microscopy (SEM) investigations with energy-dispersive X-ray spectroscopy (EDX) analysis reveals the trace of the micro-explosion related to the catastrophic SEB inside the SiC die. With a fire examination, similar to a blast, the SEM analysis discloses damages due to the large local increase of the temperature during the SEB thermal runaway, leading to the thermal decomposition of a part of the SiC MOSFET and the combustion with gaseous emissions in the device structure.

Precise and accurate electrical characterization of power electronics device die structures at the wafer level is essential to compare device operation to the design and to model reliability issues. In this paper, a parametric analysis for local electrical characterization in two dimensions for a discrete packaged commercial silicon carbide MOSFET is presented. On the cross-sectional sample, electron beam-induced current (EBIC) in a scanning electron microscope (SEM) is used to locate the pn junction of the body diode, evaluating the effect of the electron beam energy on the imaging of this area. Scanning Capacitance Microscopy (SCM) based on an Atomic Force Microscope (AFM) is employed to analyze the junction areas of the packaged silicon carbide MOSFET device. A parametric approach is proposed to reveal the local electrical properties of all layers in the MOSFET (n-, p-type, low, medium and high doping levels of doped SiC epilayers and SiC substrate and the silicon gate). The objective of the paper is to expose the potentialities of EBIC and SCM to perform comprehensive characterization of a SiC packaged device. The influence of the applied voltages (V DC and V AC ) during SCM acquisitions is investigated, in order to quantify their effect on the analysis of the doped layers of the MOSFET SiC. The nano-electrical experiments are supported by TCAD simulations of the tip/sample nano-MOS contact to confirm the interpretation in terms of doping levels of the AFM maps of the silicon carbide die.

This paper reports an evaluation of time to failure (TTF) of GaN transistors for 5G and RADAR applications. The TTF on Arrhenius curves are extrapolated from performed RF pulsed life tests with different input powers and duty cycles. The paper explains the temperature estimation method used in this study for operating conditions of the aging tests. A degradation mechanism of surface pitting is extrapolated from previous works. With our experiments, tests can show that the supposed scaling DC to RF life tests could be now extended for duty cycles. The high reliability of HEMT AlGaN/GaN on RF pulsed operating conditions is shown for a power bar of RF transistors.

Dealing with electronic devices for high reliability applications in terrestrial environments, neutron-induced Single Event Effects must be investigated. In this paper, the experimental observation of an atmospheric-like neutron-induced Single Event Burnout (SEB) on a packaged commercial SiC power MOSFET is presented after irradiation at ISIS-ChipIr. The effects of the SEB in the electrical properties of the MOSFET are established, and the SiC damaged zone is observed by scanning electron microscopy. Based on this failure analysis at the die level, the distinct stages during the SEB mechanism can be defined. The sensitive volume where the secondary particle deposited enough energy to trigger the SEB mechanism is identified and located inside the SiC n-drift epitaxial layer near the epitaxial layer/substrate junction.

This paper reports a reliability study on two technologies of AlGaN/GaN high-electron mobility transistors (AlGaN/GaN HEMTs) (Device “A” and Device “B”). A failure analysis study is conducted on devices stressed under real operating conditions for radar applications. The devices underwent pulsed-RF long ageing tests and after 11,000 h show a degradation in RF and DC performances (Drop of drain current and RF output power, pinch-off shift, decrease of the maximum of transconductance, lateral translation of transconductance, and increase of gate-lag and drain-lag). Hot electron effects are supposed to be the origin of the observed degradations and trapping phenomena within the passivation or GaN layers. Photon emission microscopy (PEM), Optical Beam Induced Resistance Change (OBIRCH), Electron Beam Induced Current (EBIC) measurements concur with this hypothesis. The three techniques reveal a non-uniform response and an inhomogeneous distribution along the gate fingers, in addition to the presence of some localized spots localized on the gate edge either on the drain side or on the source side. Spectral PEM analysis of these spots identifies a native defect that could be related to crystallographic defects such as dislocations or impurities. Atom probe tomography (APT) analysis on the two technologies of AlGaN/GaN HEMTs supports this hypothesis. APT results show the presence of some chemical impurities like carbon and oxygen. These impurities are in relatively significant concentrations in device “A” which could explain the high level of gate-lag and drain-lag in this device compared to device “B”.

This article reports a reliability study on AlGaN/GaN high-electron-mobility transistors under the RF stress. It shows a stabilization of the gate contact after the aging test. However, the degradation of RF performances and dc parameters is noticed. The degradations are mainly due to bulk traps located between gate-source or gate-drain and caused by hot-electron effects. The trap-related phenomena results in a reduction of the drain current and RF output power accompanied with transconductance degradation and pinch-off shift. These traps are characterized by gate-lag and drain-lag measurements and spectral photon emission microscopy. Photo emission measurements reveal an inhomogeneous distribution of light and the presence of native traps that could be related to crystallographic defects such as dislocations or impurities.

Progressing miniaturization and the development of semiconductor integrated devices ask for advanced characterizations of the different device components with ever-increasing accuracy. Particularly in highly doped layers, a fine control of local conduction is essential to minimize access resistances and optimize integrated devices. For this, electrical Atomic Force Microscopy (AFM) are useful tools to examine the local properties at nanometric scale, for the fundamental understanding of the layer conductivity, process optimization during the device fabrication and reliability issues. By using Scanning Capacitance Microscopy (SCM) and Scanning Spreading Resistance Microscopy (SSRM), we investigate a highly in situ doped polycrystalline silicon layer, a material where the electrical transport properties are well known. This film is deposited on a oxide layer as a passivating contact. The study of the nano-MIS (SCM) and nano-Schottky (SSRM) contacts allows to determine the distribution and homogeneity of the carrier concentration (active dopants), especially by investigating the redistribution of the dopants after an annealing step used for their activation. While the chemical analysis by Secondary Ions Mass Spectroscopy (SIMS) quantifies only the dopant concentration in the polycrystalline layer, the comparison with macroscopic characterization techniques as Hall effect measurements, supported with XRD characterization, shows that careful SCM and SSRM measurements can be used to highlight the dopant activation. This analysis gives a complete investigation of the local electrical properties of the passivating contact when the parameters (applied voltages and applied forces) of the AFM nano-contacts are correctly controlled.

This paper presents a complete methodology based on an accurate S-parameters calibration procedure to determine parasitic resistances, inductances, and capacitances of a packaged GaN power transistor. Results show the possibility to extract very low device parasitics which may influence switching mechanisms in power converters. The accuracy of the S parameter characterization is verified on a SiC power MOSFET. Good agreement is found between extracted values and technical data provided in the literature. The extracted linear model of the tested GaN HEMT is simulated in the frequency domain using an S-parameters circuit simulator. The excellent match between the measurement and simulation indicates a high accuracy of the S-parameter extraction technique. The GaN HEMT parasitic elements are obtained from the S-parameters measured using a vector network analyzer and then converted to the impedance (Z) parameters. These parameters, through detailed network analysis, provide more accurate values of the internal parasitic inductances than the commonly used LCR meter measurement technique. The method has the capability to be applied to any packaged GaN power transistor fabricated by different manufacturers.

An experimental study based on pulsed I-V characterization is conducted at various temperatures to estimate the losses of GaN High-Electron-Mobility Transistors (HEMTs) for switching circuit applications. The estimation of the GaN HEMT power losses is performed by a SPICE simulation using a non-segmented Electro-thermal model. The parameters of this model are extracted using Levenberg–Marquardt Algorithm. The proposed modeling methodology is compared to literature and shows good convergence of static characteristics. The temperature dependency of device parameters is also taken into consideration. Furthermore, the modelled device is verified in a real switching application using a developed efficient switching bench. The verification of the GaN HEMT model shows a good convergence to measurements in term of conduction power losses. Finally, the evolution of the GaN HEMT power losses in switching applications is modelled as a function of the temperature and output current.

This paper presents a method based on IV pulsed characterizations to estimate the junction temperature of AlGaN/GaN high-electron mobility transistors (AlGaN/GaN HEMTs). This technique allows a 2D plan evaluation of the average temperature of the transistor and the thermal resistance as a function of the dissipated power and the base plate temperature. In order to validate this method, our outcomes are compared with infra-red (IR) microscopy measurements realized with a Quantum Focus Instrument (QFI) Infrascope. The measured data show a good agreement with the results of our approach. Further analyses are carried out with IR microscopy to investigate the dependence of temperature on electrical parameters.

Reliability studies are fundamental to optimize the use of new emerging technologies such as AIGaN/GaN HEMTs. This paper reports a reliability study on two power amplifiers using A1GaN/GaN HEMT in real operating conditions for radar applications. Three pulsed-RF long aging tests (8000 h/11,000 h total) are performed under different conditions of (V-ds), Temperature, gain compression and Duty cycle. A following of various degradation indicators during the aging tests is presented (P-out, I-ds, I-gs, R-ds(on), G(m) and V-th). This study will contribute to establish a new reliability prediction model of GaN devices and update the FIDES guide.

In this article, the segregation of Mg to threading dislocation is demonstrated in a commercial normally-off GaN High Electron Mobility Transistor using atom probe tomography. The diffusion of Mg from a doped p-type GaN gate through the AlGaN buffer to the GaN substrate is demonstrated.

This paper proposes a methodology to study the reliability and failure analysis of new technologies of power transistors. The use of wide gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) is now a good alternative to meet the integration requirements of energy conversion systems.

This chapter presents the results of a study in which the temperature and the microdisplacements of the chip surface of high-frequency power electronic components used in radar and telecommunication systems are measured. Several techniques are applied. Their advantages, disadvantages and shared fields of application are discussed. Results from several samples show that the different approaches converge. The originality of this study is that the measurements of chip surface temperature and displacement are obtained simultaneously. This approach makes it possible to then calculate the thermal resistance of an electronic component and characterize the evolution of this resistance over component lifetime.

This paper proposes an experimental study of temperature effects on Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs).The output and transfer characteristics are monitored at temperatures ranging from 5°C to 105°C.The temperature dependency on static parameters of GaN HEMT is examined, such as: drain current (IDS), on-state resistance (RDS(ON)), transconductance (gm), threshold voltage (VTH) and the gate leakage current (IGSS).The decreases of IDS and gm accompanied with the increase of RDS(ON) and IGSS when increasing temperature have been observed.Moreover, the decrease in electron mobility with increasing temperatures is considered to be one of the causes of the reduction in the drain current and transconductance.In order to study the impact of temperature on power converters with GaN HEMTs by simulation approach, the thermal characteristics of a 650V, 30A GaN HEMT have been modelled.The used model is a nonsegmented Electro-thermal SPICE model of Motorola.The model parameters are extracted using Levenberg-Marquardt Algorithm.

This paper aims to study the SiC power MOSFETs robustness to Electrostatic Discharge (ESD), by photon emission using spectral photoemission technique (SPE). Investigations in photoemission PE reveal the degradation signature. SPE analyses are performed to identify the failure mechanism. The ESD degradation is seems to be related to oxide degradation. C-V analyses are conducted to prove this hypothesis.

In this paper, a method to estimate the junction temperature of high-electron mobility transistors (HEMTs) is proposed. This technique based on electrical measurements with IV pulsed setup take into account the dissipated power and the base plate temperature of the component. The average temperature of the transistor could be evaluated in a 2D plan with dissipated power and base plate temperature and a thermal resistance is evaluated in this 2D plan.