Arnaud Curutchet

Evidence of traps creation in GaN/AlGaN/GaN HEMTs after a 3000 hour on-state and off-state hot-electron stress

A long-term 3000-hour test under on-state conditions (VDS =25V, 6W/mm constant dissipated power) and off-state conditions (V DS=46V, VGS=-6V) on GaN/AlGaN/GaN HEMTs is presented. Trapping presence and hot-electrons effect are characterized by means of low-frequency techniques (low-frequency noise measurements, transconductance frequency dispersion, gate-lag). The on-state stress shows the most important degradation. Since our measurements point out to the creation of traps in the gate-to-drain surface region during the stress, this degradation is ascribed to the effect of hot-electrons

Robust Surface-Potential-Based Compact Model for GaN HEMT IC Design

We present an accurate and robust surface-potential-based compact model for simulation of circuits designed with GaN-based high-electron mobility transistors (GaN HEMTs). An accurate analytical surface-potential calculation, which we developed, is used to develop the drain and gate current model. The model is in excellent agreement with experimental data for both drain and gate current in all regions of device operation. We show the correct physical behavior and mathematical robustness of the model by performing various benchmark tests, such as DC and AC symmetry tests, reciprocity test, and harmonic balance simulations test. To the best of our knowledge, this is the first time a GaN HEMT compact model passing a range of benchmark tests has been presented.

AlGaN/GaN HEMT Reliability Assessment by means of Low Frequency Noise Measurements

Although impressive results have been published for GaN-based transistors in a large frequency range reliability demonstration is becoming an important subject of concern. In this article the conditions of a long term DC life test is presented and a detailed description of pre- and post-test characterization by means of Low Frequency Noise measurements (LFN) is discussed. The transistor parameters (IDSS, Ron, Vp) and the drain noise spectra presented an evolution strictly related to the biasing point during the stress. This demonstrates that LFN measurement is a useful tool to investigate degradation in GaN HEMTs.

Analysis of Schottky Gate degradation evolution in AlGaN/GaN HEMTs during HTRB stress

GaN based technologies are promising in terms of electrical performances for power and high frequencies applications and their reliability assessment remains a burning issue. Thus, a good understanding of their degradation mechanisms is required to warranty their reliability. In this paper, an electrical parasitic effect has been observed on the gate-source diode forward characteristics of a set of devices under HTRB stress carried out at 175 °C up to 4000 h. This parasitic effect has been attributed to lateral surface conduction and correlated with EL signature under diode forward biasing conditions but not under transistor pinch-off biasing conditions. Then, physical analyses have pointed out the formation and growing over time of pits and cracks at the gate edge on the drain side

Link between low frequency noise and reliability of compound semiconductor HEMTs and HBTs

On the basis of papers published on the fundamental and excess LF noise sources in compound semiconductor transistors, two main issues are addressed in this paper: i) the characterization of LF noise sources linked to parasitic effects induced by innovative component architecture in emerging technologies such as GaN-based HEMTs and GaAsSb HBTs. ii) the identification of LF noise sources linked to degradation mechanisms in compound semiconductor devices issued from mature technologies. Examples of experimental correlation between LF noise and parasitic effects (i.e. potential electrical performance penalization) or failure mechanisms in III-V HEMTs and HBTs are described with data related to recent technological developments.

Influence of gate leakage current on AlGaN/GaN HEMTs evidenced by low frequency noise and pulsed electrical measurements

The study of the pulsed drain current or noise characteristics in AlGaN/GaN HEMTs is the key of knowledge for designing the power amplifiers, the low noise amplifiers and the oscillators or mixers, but it is well accepted today that this study is not fully accomplished without pointing on the effect of the gate leakage current; It is obvious that the transistors leakage current may disturb its operation at high power and high frequency. Leakage currents studies are also an area of great importance in optimization of safe operating area and reliability of HEMTs. Therefore, room temperature pulsed I-V and low frequency noise measurements of gate and drain currents of AlGaN/GaN HEMTs have been investigated under different bias conditions on two devices showing identical drain current and different gate current levels. The results show a correlation between two non-destructive measurement techniques applied on devices under test.

Evidence of relationship between mechanical stress and leakage current in AlGaN/GaN transistor after storage test

In this paper, leakage current signatures in AlGaN HEMT are studied after storage at 300 °C. Electrical characterization of the gate to source diode as a function of the temperature has been performed on HEMT with two different gate pad topologies, but it has not allowed identifying significant difference in the electron transport mechanisms. In forward and low reverse bias, the preeminent conduction mechanism can be attributed to thermionic field emission (TFE). By localized FIB cuts, Optical Beam Induced Resistance Change (OBIRCh) analysis was used to localize current path. Results tend to indicate that mechanical stresses in the gate structure strongly influences the leakage current of the transistor. The OBIRCh analysis technique, widely used in silicon technology, appears to be a very efficient tool to localize leakage paths, in particular for HEMT topology with source terminated field plate.

Correlation between forward-reverse low-frequency noise and atypical I–V signatures in 980 nm high-power laser diodes

Highlights • We observe atypical laser diode (LD) signatures in reverse I-V measurement identified as microplasma discharges. • Correlation between reverse I-V signatures and LFN measurements appears as a complementary tool for improvement of screening methodology for LD. • Reverse and forward noise spectra especially exhibit 1/f noise. • Some lasers reveal g-r noise component in bias voltages corresponding to reverse I-V slope changes and around ITH. • Presence of g-r noise leads to believe that point defect can be localized near the active zone.

Nonlinear Characterization and Modeling of Carbon Nanotube Field-Effect Transistors

We report for the first time to our knowledge large-signal measurements performed at 600 MHz and in time domain on carbon nanotube field-effect transistors (CNFETs) using a large-signal network analyzer. To overcome the very high mismatch between the high CNFET impedance and the basic 50-Omega configuration of the setup, the output impedance was matched with the help of an experimental active load-pull configuration. Hence, we were able to observe under large-signal conditions the nonlinear behavior of CNFETs. Static measurements and continuous-wave S ij -parameter measurements were made for many different biases. They were used in order to determine a nonlinear electrical model that has been validated thanks to the nonlinear measurements. The developed model opens the way for electrical CNFET circuit simulation and nonlinear applications of these devices.

Low Frequency Noise Evolution of AlGaN/GaN HEMT after 2000 hours of HTRB and HTO life tests

The low frequency drain noise of High Electron Mobility Transistor based on AlGaN/GaN heterostructure on SiC substrate is analysed before and after 2000 hours of DC life tests. The life tests have weakly affected the drain current noise of this technology. The experimental results show that the degradation should not be located in the channel.