Search Results (10)

This study systematically investigates the mechanism by which total ionizing dose (TID) affects the lifetime degradation of NMOS devices induced by hot-carrier injection (HCI). Experiments involved Cobalt-60 (Co-60) gamma-ray irradiation to a cumulative dose of 500 krad (Si), followed by 168 h annealing at 100 °C to simulate long-term stability. However, under HCI stress conditions (V_D = 2.7 V, V_G = 1.8 V), irradiated devices show a 6.93% increase in threshold voltage shift (ΔV_th) compared to non-irradiated counterparts. According to the IEC 62416 standard, the lifetime degradation of irradiated devices induced by HCI stress is only 65% of that of non-irradiated devices. Conversely, when the saturation drain current (I_Dsat) degrades by 10%, the lifetime doubles compared to non-irradiated counterparts. Mechanistic analysis demonstrates that partial neutralization of E’ center positive charges at the gate oxide interface by hot electrons weakens the electric field shielding effect, accelerating ΔV_th drift, while interface trap charges contribute minimally to degradation due to annealing-induced self-healing. The saturation drain current shift degradation primarily correlates with electron mobility variations. This work elucidates the multi-physics mechanisms through which TID impacts device reliability and provides critical insights for radiation-hardened design optimization. Full article

As application conditions become increasingly demanding and usage becomes more aggressive, the performance of traditional insulated gate bipolar transistor (IGBT) and fast recovery diode (FRD) systems can no longer meet the required specifications. In these systems, FRDs are required to carry load current and allow current to return from the load to the IGBTs. Consequently, the reverse recovery performance of the FRDs significantly restricts the overall efficiency of the system. Therefore, how to predict the reverse recovery characteristics of the FRDs with greater precision has attracted considerable attention. In this context, this paper presents an in-depth investigation of the high-level injection carrier distribution and reverse recovery characteristics of punchthrough P-I-N (PT-PIN) FRD with a buffer layer. Specifically, the research explores the physical properties of the materials, doping concentrations, and the geometric structure of the devices. Furthermore, it takes into account the complex interactions among carrier recombination, diffusion, and drift, leading to the development of a model that delineates the spatial distribution of carriers and their influence on current conduction. Building upon the traditional step-wise analysis method, subsequently, the temporal aspects of the FRDs reverse recovery process were further segmented. Utilizing the derived carrier distribution model, a reverse recovery analytical model was constructed. The model was validated using a 1200 V, 100 A IGBT with 1200 V, 60 A FRD configured in a reverse parallel arrangement, which demonstrated a 5% improvement in prediction accuracy of V_R compared with previous models that employed the lumped charge method. Finally, a range of experiments with varying R_G, V_CC and I_F confirmed the broad applicability of this analytical model. Full article

This paper presents a reliability study of a conventional 650 V SiC planar MOSFET subjected to pulsed HTRB (High-Temperature Reverse Bias) stress and negative HTGB (High-Temperature Gate Bias) stress defined by a TCAD static simulation showing the electric field distribution across the SiC/SiO₂ interface. The instability of several electrical parameters was monitored and their drift analyses were investigated. Moreover, the shift of the onset of the Fowler–Nordheim gate injection current under stress conditions provided a reliable method to quantify the trapped charge inside the gate oxide bulk, and it allowed us to determine the real stress conditions. Moreover, it has been demonstrated from the cross-correlation, the TCAD simulation, and the experimental ΔV_th and ΔV_FN variation that HTGB stress is more severe compared to HTRB. In fact, HTGB showed a 15% variation in both ΔV_th and ΔV_FN, while HTRB showed only a 4% variation in both ΔV_th and ΔV_FN. The physical explanation was attributed to the accelerated degradation of the gate insulator in proximity to the source region under HTGB configuration. Full article

The ring current region in the Earth’s magnetosphere contains energetic charged particles, which are injected from the magnetotail, get trapped in the inner magnetosphere, and finally drift around the Earth. The current, essentially carried by ions, is caused by the differences between the drift of the positively charged ions and that of negatively charged electrons. The charge exchange that occurs between ring current ions and geocoronal atoms determines the distribution and evolution of the ring current and lays the basis for remote detection techniques. By measuring the energetic neutral atoms produced by the charge-exchange process, the ring current can be remotely detected via energetic neutral atom imaging. The Chinese Double Star Program operated the NeUtral Atom Detector Unit (NUADU) onboard one of its two satellites for more than four years. A variety of studies were conducted using multiple methods applied to observations, such as intuitive image inspection, forward modeling, and inversion. Energetic neutral atom imaging was established as a promising technique for future imaging projects. Full article

The dynamics of the positive ions created by particle interactions inside argon time projection chambers plays an important role in characterizing the next generation of massive detectors planned for the direct search for dark matter and the study of neutrino properties. We have constructed a 1 L liquid argon chamber (ARION: ARgon ION experiment) with a high voltage pulse generator capable of injecting, in a controlled manner, a sizeable ion current into the drift region. This chamber is capable of reproducing a volume charge similar to that found in large detectors, allowing its effects to be studied systematically. New experimental results regarding ion dynamics in the liquid and direct demonstration of ion feedback from the gas to the liquid are discussed in this paper. In addition, a novel technique to measure the drift velocity of argon ions is introduced along with preliminary results obtained in gas. Full article

We describe some modifications to a Bernas-type ion source that improve the ion beam production efficiency and source operating lifetime. The ionization efficiency of a Bernas type ion source has been improved by using a small anode that is a thin rod, oriented along the magnetic field. The transverse electric field of the small anode causes the plasma to drift in the crossed ExB field to the emission slit. The cathode material recycling was optimized to increase the operating lifetime, and the wall potential optimized to suppress deposition of material and subsequent flake formation. A three-electrode extraction system was optimized for low energy ion beam production and efficient space charge neutralization. An ion beam with emission current density up to 60 mA/cm² has been extracted from the modified source running on BF₃ gas. Space charge neutralization of positive ion beams was improved by injecting electronegative gases. Full article

This paper presents a novel full-depletion Si X-ray detector based on silicon-on-insulator pixel (SOIPIX) technology using a pinned depleted diode structure, named the SOIPIX-PDD. The SOIPIX-PDD greatly reduces stray capacitance at the charge sensing node, the dark current of the detector, and capacitive coupling between the sensing node and SOI circuits. These features of the SOIPIX-PDD lead to low read noise, resulting high X-ray energy resolution and stable operation of the pixel. The back-gate surface pinning structure using neutralized p-well at the back-gate surface and depleted n-well underneath the p-well for all the pixel area other than the charge sensing node is also essential for preventing hole injection from the p-well by making the potential barrier to hole, reducing dark current from the Si-SiO₂ interface and creating lateral drift field to gather signal electrons in the pixel area into the small charge sensing node. A prototype chip using 0.2 μm SOI technology shows very low readout noise of 11.0 e⁻_rms, low dark current density of 56 pA/cm² at −35 °C and the energy resolution of 200 eV(FWHM) at 5.9 keV and 280 eV (FWHM) at 13.95 keV. Full article

Capacitor and Schottky diode sensors were fabricated on GaN material grown by hydride vapor phase epitaxy and metal-organic chemical vapor deposition techniques using plasma etching and metal deposition. The operational characteristics of these devices have been investigated by profiling current transients and by comparing the experimental regimes of the perpendicular and parallel injection of excess carrier domains. Profiling of the carrier injection location allows for the separation of the bipolar and the monopolar charge drift components. Carrier mobility values attributed to the hydride vapor phase epitaxy (HVPE) GaN material have been estimated as μ_e = 1000 ± 200 cm²/Vs for electrons, and μ_h = 400 ± 80 cm²/Vs for holes, respectively. Current transients under injection of the localized and bulk packets of excess carriers have been examined in order to determine the surface charge formation and polarization effects. Full article

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μ_e = 4000 cm²/Vs and holes μ_h = 3800 cm²/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion D_a = 97 cm²/s and the carrier recombination lifetime τ_R,CVD ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τ_R,HPHT ≌ 2 ns prevails in HPHT diamond. Full article

The problem of drifting charge-induced currents is considered in order to predict the pulsed operational characteristics in photo-and particle-detectors with a junction controlled active area. The direct analysis of the field changes induced by drifting charge in the abrupt junction devices with a plane-parallel geometry of finite area electrodes is presented. The problem is solved using the one-dimensional approach. The models of the formation of the induced pulsed currents have been analyzed for the regimes of partial and full depletion. The obtained solutions for the current density contain expressions of a velocity field dependence on the applied voltage, location of the injected surface charge domain and carrier capture parameters. The drift component of this current coincides with Ramo’s expression. It has been illustrated, that the synchronous action of carrier drift, trapping, generation and diffusion can lead to a vast variety of possible current pulse waveforms. Experimental illustrations of the current pulse variations determined by either the rather small or large carrier density within the photo-injected charge domain are presented, based on a study of Si detectors. Full article