1,721,564 research outputs found
A novel technique to alleviate the stiction phenomenon in radio frequency microelectromechanical switches
No full textRadio frequency (RF) microelectromechanical system (MEMS) switches subject to long term actuation suffer from narrowing of the actuation and release voltages. This can lead to the failure of the device when the device remains actuated without external biasing due to stiction effects. The stiction phenomenon is one of the most challenging problems in RF MEMS switches, especially in applications where these devices have to remain actuated for an extended period of time (months or even years). In this letter, we show a novel recovery technique to alleviate the stiction phenomenon significantly increasing the device lifetime. In particular, we show how the flowing of a small current through the suspended membrane can be used to fully restore the device properties to its fresh conditions in just a few seconds
Electroluminescence and other diagnostic techniques for the study of hot-electron effects in compound semiconductor devices
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Expected Life and Failure Model in IGBT Modules under Vibration-Induced Stress: A Case Study
No full textThis article presents a case study on a gel-filled insulated gate bipolar transistor (IGBT) module under mechanical vibration, focusing on its failure mechanism and proposing a life model. First, we used finite element analysis (FEA) with ANSYS to predict the critical stress points, which turned out to be the bond wire feet. Second, we validated these findings to a high degree through experimental tests using a vibrating chamber. In both approaches, a strong correlation is found between the failure rate and the vibration profile, where wear rate increases as one approaches the bond wires' resonance frequency. In experimental tests, all samples happened to fail at the same location, i.e., the upper side foot of terminal bond wires. This result matches the simulation predictions, as these bond wires are the ones with the lowest resonance frequency, hence the closest to the real-world vibrations. A comparison between simulation and experimental results suggest that silicone gel adds to the system a beneficial low-pass behavior that is expected to extend bond wires lifespan
Impact wear and other contact effects on the electro-mechanical reliability of MEMS
No full textWithin reliability issues in the MEMS field, the contact problem is one of the most complex to model and validate. In fact, it is influenced by many electro-thermo-mechanical parameters that make extremely difficult to predict the damaging effects on the involved surfaces and its implications on the device performances and reliability. The goal of this paper is to analyze the impact wear and the other effects of contact on the electro-mechanical properties of MEMS by means of dedicated experiments. Long term tests of repetitive impact loading are reported with the goal of relating the excitation parameters to the electrical RF performances degradation of the devices due to impact effects on electrode surface
TCAD modeling of bias temperature instabilities in SiC MOSFETs
Full text linkTCAD simulations of SiC power MOSFETs have been performed to study the dependence of positive-bias temperature instability (PBTI) on temperature and electric field. The model used to describe the kinetics of the transition rates between neutral and charged traps is the extended Non-Radiative Multi Phonon (eNMP). Connections between oxide defect configurations at the interface with SiC substrate have been made. Validation against experiments is shown
Current collapse and high-electric-field reliability of unpassivated GaN/AlGaN/GaN HEMTs
No full textLong-term ON-state and OFF-state high-electric-field stress results are presented for unpassivated GaN/AlGaN/GaN high-electron-mobility transistors on SiC substrates. Because of the thin GaN cap. layer, devices show minimal current-collapse effects prior to high-electric-field stress, despite the fact that they are not passivated. Thin comes at the price of a relatively high gate-leakage current. Under the assumption that donor-like electron traps are present within the GaN cap, two-dimensional numerical device simulations provide an explanation for the influence of the GaN cap layer on current collapse and for the correlation between the latter and the gate-leakage current. Both ON-state and OFF-state stresses produce simultaneous current-collapse increase and gate-leakage-current decrease, which can be interpreted to be the result of gate-drain surface degradation and reduced gate electron injection. This study shows that although the thin GaN cap layer is effective in suppressing surface-related dispersion effects in virgin devices, it does not, per se, protect the device from high-electric-field degradation, and it should, to this aim, be adopted in conjunction with other technological solutions like surface passivation, prepassivation surface treatments, and/or field-plate gate
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