Current Injection Mode Research Articles

Load Current Injection Modes Affected Power Cycling Lifetime and Failure Mechanism of IGBTs

In this paper, the influence of load current injection modes (saturation mode and threshold mode), at standard DC power cycling, on the failure mechanism and lifetime of IGBTs is presented. 6 groups of power cycling tests, at almost the same test conditions, with 2 different current injection modes and 2 different packages are performed. The failure mode after power cycling is confirmed by on-line monitored electrical and thermal parameters (forward voltage drop <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CE</sub> and thermal resistance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thjs</sub> ) and further by SAM (Scanning Acoustic Micrography) pictures. Failure mechanism is then analyzed and the power cycling lifetime is compared and explained, with the help of finite element simulations. All results show that the threshold load current injection mode, with the gate and collector shorted, in power cycling can indeed reduce the load current to a large extent for the desired junction temperature swing. However, the power cycling lifetime and failure mechanism are changed, especially for devices with bond wire failure. It is not recommended for power cycling lifetime evaluation.

Spatial electric potential distributions and damage mapping in 3D carbon fiber/epoxy angle-interlock woven composites with different current directions

Exploring electric potential distributions in carbon fiber reinforced polymer composites (CFRPs) is important in electrical-based structural health monitoring for in situ damage detection. Here we investigate influences of current injection angles, electrode locations, and current injection pairs on the electric potential distributions in 3D carbon fiber/epoxy angle-interlock woven (AIW) composites. We have conducted different types of electric potential measurements and established a linear anisotropic conductivity model to reveal the electric potential distributions. It was found that the curved warp yarns form many contacts and increase the conduction path, leading to lower electric conductivity and flatter potential field than those of the weft yarn with straight alignment. The orientation and value of surface electric potential field change depend on current flow direction caused by current injection mode (CIM) and conduction mechanism due to yarn arrangement. Oblique current directed at an angle of 45° is more sensitive in indicating interior damage than that of current parallel to the yarn direction. It is recommended that the oblique current injection should be used to provide effective damage sensing for CFRPs with complex structures.

Abstract 5484: Influence of the thermal and electric properties of biological tissues on the maximum temperature during TTFields therapy

Abstract Tumor Treating Fields (TTFields) is a non-invasive technique used in the treatment of glioblastoma. It consists in applying an electric field with a frequency of 200 kHz in two perpendicular directions alternately. This technique has an anti-mitotic effect if the induced field is at least 1 V/cm at the tumor bed. The Optune device, used to deliver these fields in real subjects, controls the injected current to keep scalp's temperature below potentially harmful values by controlling the temperature of the transducers. The thermal impact of this technique was recently predicted by our group. In this work we aim to investigate how the uncertainties regarding both the electric and thermal properties of tissues, transducers and gel affect the maximum temperature reached by each tissue and might affect the time that the device is applying the fields due to its thermal restrictions. We used a realistic head model created from MR images to perform our studies and run the simulations in COMSOL Multiphysics. After an extensive literature review, we selected a reasonable range of values for each property and performed a one-way sensitivity analysis. To obtain the temperature distribution we solved Pennes' equation in frequency domain studies. We observed that the most significant electric parameters are scalp, skull and gel's conductivity values. In general, an increase in the conductivity led to higher temperatures, as expected. In terms of changes in the temperature reached by the transducers it was seen that it can vary between +1.3°C (when scalp's conductivity is increased by a factor of 80% to 0.45 S/m) and -1.7°C (scalp's conductivity decreased to 0.14 S/m). The thermal parameters that are more critical are the ones that can directly change how quickly heat is transferred to the environment, namely scalp's properties. Transducer temperature varied between -0.6°C and +1.3°C when scalp's thermal conductivity was increased by 46% and decreased by 53%, respectively. Furthermore, the sweat rate and the convection factor and emissivity of the medical tape that covers the arrays also led to significant temperature variations. The latter analysis can be used to study new types of materials that can be more appropriate to apply these fields. The remaining electric (relative permittivity) and thermal (metabolic heat, blood perfusion, blood density and specific heat and thermal conductivity of skull, CSF and brain) parameters did not lead to significant temperature variations. These results show the importance of precisely knowing the most crucial physical properties in TTFields modelling studies. Due to the very strict current control injection mode of Optune based on the temperature of the transducers, it would be beneficial to experimentally measure the properties here discussed. Citation Format: Nichal Gentilal, Pedro Cavaleiro Miranda. Influence of the thermal and electric properties of biological tissues on the maximum temperature during TTFields therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5484.

MILLIMETER WAVE DETECTORS DEVELOPED ON THE BASIS OF DOPED SEMICONDUCTORS

Semiconductor p-i-n structure with long i-base region doped with shallow donors/acceptors can be successfully used and have significant advantages in millimeter wave range as cooling THz receivers. It is shown that such detectors working in double current injection mode can have high current photosensitivity and detectivity, linear dependencies of sensitivity versus wavelength and applied voltage. Simulation results can be successfully used for detectors fabricated on the basis of several semiconductors: Si : Li , Si : O , Ge : B , Ge : Al , Ge : Ti , Ge : Be , Ge : P , Ge : As , Ge : Sb , GaAs : Li , GaAs : Zn , GaAs : Cd , GaAs : X , GaP : N , which covered wavelengths 40–200 μm. The simulation results made in this paper have demonstrated the ability of double injection structures to perform as practical and sensitive power detectors for THz radiation.

Induced magnetic moment of Eu3+ ions in GaN

Magnetic semiconductors with coupled magnetic and electronic properties are of high technological and fundamental importance. Rare-earth elements can be used to introduce magnetic moments associated with the uncompensated spin of 4f-electrons into the semiconductor hosts. The luminescence produced by rare-earth doped semiconductors also attracts considerable interest due to the possibility of electrical excitation of characteristic sharp emission lines from intra 4f-shell transitions. Recently, electroluminescence of Eu-doped GaN in current-injection mode was demonstrated in p-n junction diode structures grown by organometallic vapour phase epitaxy. Unlike most other trivalent rare-earth ions, Eu3+ ions possess no magnetic moment in the ground state. Here we report the detection of an induced magnetic moment of Eu3+ ions in GaN which is associated with the 7F2 final state of 5D0→7F2 optical transitions emitting at 622 nm. The prospect of controlling magnetic moments electrically or optically will lead to the development of novel magneto-optic devices.

The electrical delivery of a sublimable II–VI compound by vapor transport in carbon nanotubes

Progress in the field of femtogram (10 −15 g) mass delivery relies on finding dependable transport vehicles and uncomplicated methods to tailor the deposition of active substances. Here, current-conductive containers consisting of turbostratic carbon nanotubes were used to store a light-emitting ternary alloy and guide its delivery on demand. We found that the electrically-activated delivery process of this sublimable compound, performed inside a transmission electron microscope, was highly dependent on factors such as the substrate type and current injection mode. Furthermore, our observations suggest that the alleged “missing matter” problem is not solely due to surface migration. Besides extending the field of electrical delivery to the realm of functional materials, the extrusion and mass transport of a sublimable II–VI compound demonstrates that it is possible to guide vapor migration using a carbon nanotube support.

Enhancement of light emission from silicon nanocrystals by post-O2-annealing process

This study investigated the effects of the post-O2-annealing process on light emission from silicon nanocrystals. Using pulsed laser ablation in an O2-filled atmosphere, the SiOx (x&amp;lt;2) thin layers were synthesized prior to O2-annealing. We observed a strong photoluminescence from the silicon nanocrystals embedded in the annealed layers at 500 °C, which depended on the post-O2-annealing time. We also found that the interface property between the silicon nanocrystal and stoichiometric SiO2 matrix is critical for efficient light emission. The electroluminescence spectra in the visible range were obtained above the on-current density of 0.7 A/cm2 under several forward-bias voltages. The blueshift in the electroluminescence was attributed to the band-filling effect under high current injection mode. The external emission efficiency was estimated to be about 0.3% by using the band-filling model.

Properties of inductance and magnetic penetration depth in (103)-orientedYBa2Cu3O7−δthin films

We present a study of the anisotropy of the inductance in (103) ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (YBCO) films. YBCO superconducting quantum interference devices (SQUIDs) were fabricated by the biepitaxial technique. SQUIDs with (001)- and (103)-oriented YBCO electrodes characterized by different grain-boundary angles were realized on the same chip. Two extrainjection lines were attached to the (103) YBCO electrode. These devices, when operated in current injection mode, allow us to measure the inductance of the (103) YBCO electrode. We have found that the inductance $L$ of the (103) YBCO can differ by a factor of 20 in the two extreme cases: $L$ determined by current transport parallel to the $ab$ planes and $L$ dominated by the transport in the $c$-axis direction. The full in-plane angular dependence of the inductance has been obtained by considering geometrically identical SQUIDs oriented with different angles with respect to the [100] direction of the (103) film. From these measurements, we have determined the London penetration depths in the $ab$ direction ${\ensuremath{\lambda}}_{ab}$ and the $c$ direction ${\ensuremath{\lambda}}_{c}$ and their temperature dependence.

Cryogenic detector modules and edgeless silicon sensors

We are studying the operation of silicon microstrip detector with readout electronics in the temperature range from 90 to 130 K. The sensor can be operated in the current-injection mode which significantly improves its radiation hardness. A first module prototype has been built, with APV25 readout chips and an embedded microtube, providing efficient low-mass cooling of the whole module with a two-phase flow of N 2 or Ar. First pedestal and pulse shape temperature dependencies are presented for this module. We have also built an edgeless test module with two pairs of laser cut sensors, with both angular and parallel cuts with respect to the strips (at 120 μ m pitch). We are studying the efficiency of the microstrip sensors very close ( < 200 μ m ) to the physical border of the cut silicon crystal and present here some electrical characteristics.

Electrical and Optical Characteristics of an a-Si:H/c-Si Heterojunction Switch

A novel structure of a three-terminal a-Si:H(p+-i-n)/c-Si(p-n) heterojunction threshold switching device is developed. The device can be controlled both by a voltage-controlled mode and a current-injection mode. The voltage control gain and current triggering capability are 0.9 and 5×10-3 V/µA, respectively. When this switching device is operated as an optical switch, the light triggering sensitivity is 5.8×10-3 V/µW.

Current-injection three-terminal GaAs regenerative switches

Gallium arsenide p+ –n−–δ(p+)–n−– n+ regenerative switches prepared by molecular beam epitaxy are demonstrated. Initially, their operation as an optical switch is considered. The position of a third-electrode (gate) profoundly influences the switching behaviours. Current-injection mode is then discussed. Silicon controlled rectifier (SCR)-like switches can be obtained. Comparisions are made by defining the control efficiency.

Design of a single electrode voltage clamp

The detailed schematic diagrams and construction techniques are presented for a single microelectrode voltage clamp. The device is used to study the membrane processes of small cells not able to be penetrated with the traditional two microelectrode system. The technique utilizes the same microelectrode alternately for current injection and membrane potential sampling on a time-sharing basis controlled by electronic switching circuitry. Current is injected in pulses and the membrane potential is sampled after an individual current pulse discharges from the microelectrode capacitance to the true membrane potential. The device can either measure the voltage response to an injected current waveform (current injection mode) or the membrane currents generated during a controlled change in membrane potential (voltage clamp mode). In voltage clamp mode, the membrane potential reaches steady-state within 2 msec (maximum time) in response to a 40 mV step command. The single electrode voltage clamp is potentially very important to the investigation of slow current processes within electrically excitable cells too small to be previously studied with traditional voltage clamp technology.

Transient analysis of electrical charge injection into charge-coupled devices

A detailed study of signal-charge injection into surface channel CCDa as a response to a gate-voltage step was carried out. The analysis is based on the time dependent diffusion equation with the fringing field term included. With the appropriate boundary conditions, this equation was applied to the input diffusion, input gate and succeeding gate of a CCD. It was found that injection of signal-charge into the device is characterized by three distinct processes, First is the transient-time required by the input diffusion to establish a constant injection-current under the input gate, then, the input stage enters into a constant current injection mode, and finally when the surface potentials of the input and receiving gates equalize, the injection current decays to zero. An analytical expression for the transient component, and for the total time required to inject a packet of charge into the CCD is derived.Experimental results carried out on a CCD shift register with various methods of charge injection, su...