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The shallow interface trap density near the conduction band in silicon carbide (SiC) metal-oxidesemiconductor (MOS) structure was evaluated by making capacitance-voltage measurements with gate-controlled-diode configuration using the n-channel MOS field effect transistors (MOSFETs). The close correlation between the channel mobility and the shallow interface trap density was clearly found for the 4H- and 6H-SiC MOSFETs prepared with various gate-oxidation procedures. This result is strong evidence that a significant cause of the poor inversion channel mobility of SiC MOSFETs is the high density of shallow traps between the conduction band edge and the surface Ferrai level at the threshold. [ABSTRACT FROM AUTHOR]

Temperature dependence of threshold voltage in n-channel SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) was studied. Linear relation was observed between the threshold voltage shift when the temperature varies from -150 to 150 °C and the number of the interface states present within the energy range of 0.2–0.4 eV from the conduction band edge energy E[sub c]. This relationship revealed that the interface state profile near E[sub c] in n-channel SiC MOSFETs can be represented by that in n-type SiC MOS capacitors. The relationship between the channel mobility and the interface state profile also suggested that the interface states within the energy range of 0.2–0.4 eV from E[sub c] have little influence on the channel mobility. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the microstructure of ion implanted silicon at room temperature using cross-sectional transmission electron microscopy. Presence of buried amorphous layers; Characterization of damaged layers adjacent to the amorphous layers; Atomic structure of the damaged regions.

Provides information on a study which investigated structural changes and electrical activation processes in eight megaelectronvolts phosphorus ion implanted hydrogen-silicon carbide. Significance of silicon carbide in electronics; Substrates used in the study; How the implanted layers were measured.

Introduction: The celiac plexus block is effective for treating intractable cancer pain and has been the focus of many studies. At our affiliated institution, fluoroscopy-guided splanchnic nerve block with a single needle via the transintervertebral disc approach was the first choice of treatment. The short-term efficacy of this technique has been reported, but the long-term efficacy is not clear. In the present study, we investigated the long-term analgesic efficacy of this technique. Methods: This multicenter, retrospective, observational study reviewed the medical records of patients who underwent neurolytic splanchnic nerve block (NSNB) via the transintervertebral disc approach for intractable cancer pain at five tertiary hospitals in Japan from April 2005 to October 2020. The primary outcome was the long-term analgesic efficacy of a one-time NSNB via the transintervertebral disc approach. Results: In total, 76 patients were included in the analysis. The median lowest numerical rating scale (NRS) score was 1 within 14 days. At 1, 2, 3, and 6 months after the nerve block, the median NRS score was also ≤ 2, while the median equivalent oral morphine dose did not show any clinically noticeable increase at those times. Conclusion: The long-term analgesic efficacy of NSNB via the transintervertebral disc approach in patients with intractable cancer pain has been demonstrated. Plain Language Summary: The celiac plexus block is effective for treating intractable cancer pain and has been the focus of many studies. The celiac plexus nerve block relieves intractable cancer pain arising from the pancreas or other organs in close proximity, and the splanchnic nerve block is considered clinically equivalent to the celiac plexus block for analgesia. At our affiliated institution, fluoroscopy-guided neurolytic splanchnic nerve block with a single needle via the transintervertebral disc approach is the first choice of treatment because it is technically simpler and less invasive than other approaches. While the short-term efficacy of this technique is known, its long-term efficacy remains unclear. Thus, this multicenter, retrospective, observational study aimed to investigate the long-term analgesic efficacy of a neurolytic splanchnic nerve block via the transintervertebral disc approach. The medical records of patients in whom intractable cancer pain was managed using this technique at five tertiary hospitals in Japan were analyzed. The primary outcome was the long-term analgesic efficacy of a one-time neurolytic splanchnic nerve block via the transintervertebral disc approach. The median lowest numerical rating scale score was 1 within 14 days. At 1, 2, 3, and 6 months after the nerve block, the median numerical rating scale score was also ≤ 2, while the median equivalent oral morphine dose did not show any clinically noticeable increase at those times. This technique may reduce opioid dose and associated side effects compared with long-term conventional pharmacotherapy alone. [ABSTRACT FROM AUTHOR]

Here we show, for the first time, a significant improvement of switching characteristics in a 1.2‐kV SiC Schottky barrier diode‐wall integrated trench MOSFET (SWITCH‐MOS) by the application of a Kelvin source (KS) connection. Turn‐on loss (Eon) was greatly reduced, with superior Eon‐dVDS/dt trade‐off characteristics at a moderate dVDS/dt value of about 10 kV/μs, because the SWITCH‐MOS with KS achieves a more suppressed peak reverse recovery current in embedded Schottky barrier diodes even at a higher dID/dt during the turn‐on operation than a state‐of‐the‐art SiC trench MOSFET with KS. This feature is a peculiarity of the SWITCH‐MOS when the KS connection is applied. Notably, measured and calculated results confirmed that the SWITCH‐MOS with KS had less dissipated turn‐off loss, especially in a second half of turn‐off regions (Region 2), than the SWITCH‐MOS w/o KS. However, owing to a higher negative turn‐off dID/dt, the MOSFET with KS has a larger drain surge voltage. With an optimum gate resistance, the SWITCH‐MOS with KS has 8% less total switching loss than a SWITCH‐MOS without KS, and 29% less than a state‐of‐the‐art SiC trench MOSFET with KS, while keeping a moderately low dVDS/dt of 10 kV/μs and suppressing a drain peak voltage of <720 V. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Purpose : Few reports on opioid withdrawal (OW) due to opioid tapering in cancer patients have been published. The incidence of and risk factors for OW after neurolytic splanchnic nerve block (NSNB) are unknown. This study aimed to elucidate the incidence of and risk factors for OW among cancer patients who could have reduced opioid doses after NSNB. Methods: This was a multicenter, retrospective, observational study. We reviewed the medical charts of patients who underwent NSNB for intractable cancer pain at four tertiary hospitals in Yokohama City from April 2005 to October 2020. We included patients whose opioid dose was reduced by > 5 mg/day (equivalent oral morphine dose) within 14 days after NSNB. We classified the patients into two groups according to the presence or absence of OW symptoms and compared them. Results: Of the 50 patients who underwent NSNB, 24 were included in the study. OW was observed in five (20.8%) patients. Pain and opioid use duration were significantly longer in OW patients than in non-OW patients (median pain duration 689 vs. 195 days; P < 0.043 and median opioid use duration 486 vs. 136 days; P < 0.030). The opioid tapering dose was significantly larger in patients with OW than in those without OW (median opioid tapering dose 75 vs. 40 mg; P < 0.046). Conclusions: OW was observed in 20.8% of the patients in the study. A longer pain and opioid use duration and a larger opioid tapering dose may predispose patients to OW. [ABSTRACT FROM AUTHOR]

The channel mobility in the SiC MOSFET degrades on the rough surface of the p-well formed by ion implantation. Recently, we have developed a double-epitaxial MOSFET (DEMOSFET), in which the p-well comprises two stacked epitaxially grown p-type layers and n-type region between the p-wells is formed by ion implantation. This device exhibited a low on-resistance of 8.5 mΩcm2 with a blocking voltage of 600 V. In this study, to further improve the performance, we newly developed a device structure that we named implantation and epitaxial MOSFET (IEMOSFET). In this device, the p-well is formed by selective high-concentration p+ implantation and following low-concentration p- epitaxial growth. Fabricated IEMOSFET with a buried channel exhibited superior characteristics than DEMOSFET. The extremely low specific on-resistance of 4.3 mΩcm2 was achieved with a blocking voltage of 1100 V. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(3): 9– 14, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10068 [ABSTRACT FROM AUTHOR]

Introduction: Celiac plexus block is effective for treating intractable cancer pain and has been the focus of many studies. Several guiding techniques such as fluoroscopy, computed tomography, and endoscopy have been devised, and the target of the block has varied in previous studies as both the celiac plexus and splanchnic nerve, which is the main origin of the celiac plexus, have been targeted. At our affiliated institution, fluoroscopy-guided splanchnic nerve block with a single needle via transintervertebral disc approach is the first choice. However, there have been few reports on the use of this technique. This study investigated the efficacy and safety of this technique. Methods: This multicenter retrospective observational study reviewed the medical records of patients who underwent neurolytic splanchnic nerve block (NSNB) via transintervertebral disc approach for intractable cancer pain at five tertiary hospitals in Japan from April 2005 to October 2020. The primary outcome was the clinical success ratio of NSNB, and the secondary outcome was the incidence ratio of NSNB-related adverse events. Results: In total, 103 patients were included in the analysis. Of these, 77 patients met the definition of clinical success, with a ratio of 74.8%. The incidence ratio of NSNB-related adverse events was 40.8% (hypotension, 21.4%; alcohol intoxication, 13.6%; diarrhea, 11.7%; and vascular puncture, 3.9%; duplicates were present). All adverse events improved with observation and symptomatic treatment only. No patient had infection or serious adverse events such as organ or nerve damage. Conclusions: The clinical success ratio of this technique was 74.8%. Although the incidence of adverse events was 40.8%, all events were mild and no serious adverse events were observed. The findings demonstrate the efficacy and safety of our NSNB in patients with intractable cancer pain. Plain Language Summary: In patients with intractable pain from abdominal cancer, fluoroscopy-guided neurolytic splanchnic nerve block via transintervertebral disc approach is an effective and safe procedure. It can be completed with a single needle puncture, and is anatomically less likely to cause organ or nerve damage compared with other approaches. The analgesia produced by this technique, along with conventional pharmacotherapy for cancer pain, may reduce opioid dose and its side effects and improve patients' quality of life. [ABSTRACT FROM AUTHOR]

Microstructures of recrystallized layers in 8 MeV Si3+ ion implanted 6-H-SiC (0001) wafers have been characterized by means of transmission electron microscopy. Epitaxial recrystallization of buried amorphous layers was observed at annealing temperature as low as 1000 °C. Layer-by-layer epitaxy of 6H-SiC initially occurred and it was changed to columnar growth when layer-by-layer growth exceeded 100 nm in thickness. From the microdiffraction analysis, it was found that the columnar regions are defected 6H-SiC with crystal orientations different from the substrate. In addition to 6H-SiC, epitaxial 3C-SiC was also confirmed in the recrystallized layer. Based on these results, we have proposed a structure model of the recrystallized layer in which stacking faults in the columnar regions are induced by mismatched connections between the columnar and layered 6H-SiC regions. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this work, the origin of the low free electron mobility in SiC MOSFETs is investigated using the scattering theory of two-dimensional electron gases. We first establish that neither phonon scattering nor Coulomb scattering can be the cause of the low observed mobility in SiC MOSFETs; we establish this fact by comparing the theoretically calculated mobility considering these effects with experimental observations. By considering the threshold voltages and the effective field dependence of the mobility in SiC MOSFETs, it is concluded that the scattering centers of the dominant mechanism are electrically neutral and exhibit a short-range scattering potential. By considering a charge distribution around a neutral defect at the interface, it is established that an electric dipole induced by the defect can act as a short-range scattering potential. We then calculate the mobility in SiC MOSFETs assuming that there exists a high density of dipoles at the interface. The calculated dipole-scattering-limited mobility shows a similar dependence on the effective field dependence to that observed in experimental results. Thus, we conclude that scattering induced by a high density of electric dipoles at the interface is the dominant cause of the low mobility in SiC MOSFETs. [ABSTRACT FROM AUTHOR]

The reason for the effective removal of interface traps in SiO/4H-SiC (0001) structures by boron (B) incorporation was investigated by employing low-temperature electrical measurements. Low-temperature capacitance-voltage and thermal dielectric relaxation current measurements revealed that the density of electrons captured in slow interface traps in B-incorporated oxide is lower than that in dry and NO-annealed oxides. These results suggest that near-interface traps can be removed by B incorporation, which is considered to be an important reason for the increase in the field-effect mobility of 4H-SiC metal-oxide-semiconductor devices. A model for the passivation mechanism is proposed that takes account of stress relaxation during thermal oxidation. [ABSTRACT FROM AUTHOR]

We investigated the effects of the column length and fabrication method of the superjunction (SJ) structure on the reverse recovery characteristics of 1.2 kV silicon carbide (SiC) SJ metal–oxide–semiconductor field-effect transistors (MOSFETs). The voltage slope (dV/dt) and reverse recovery current slope (dir/dt) values during the reverse recovery of the SJ-MOSFETs with the SJ structure formed by Aluminum (Al) ion implantation were comparable to the values of MOSFETs without SJ structure at room temperature (RT), but they increased markedly with temperature. This is caused by the reduced p-column carrier concentration at RT during short recovery transient time due to the deep hole trap (D I center) introduced by ion implantation. At 175 °C, a softer reverse recovery waveform was obtained by shortening the SJ columns. Besides, Al ion implanted SJ-MOSFETs exhibited a weaker current dependence of the reverse recovery charge Q rr at 175 °C indicating a lower carrier injection level compared to the SJ-MOSFETs with the SJ structure formed by trench formation and epitaxial growth. This is caused by the short carrier lifetime of the SJ columns due to the Al ion implantation defects. The short and Al ion implanted SJ columns are effective for soft reverse recovery characteristics in SiC-SJ-MOSFETs. [ABSTRACT FROM AUTHOR]

Color centers in silicon carbide (4H-SiC) are potentially usable as spin defects for quantum sensing and quantum information technology. In particular, neutral divacancies (the P6/P7centers, VSiVC0) and a certain type of silicon vacancies (the TV2a center, VSi- at the k site) are promising for addressing and manipulating single spins. Although the TV2a spin is readable at room temperature, the readout techniques have been limited to luminescence-based ones (e.g., optically detected magnetic resonance). In this study, we demonstrated electrical detection of TV2a-type silicon vacancies at room temperature by using electrically detected magnetic resonance on 4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs). TV2a spin defects were embedded in the channel region of well-defined 4H-SiC MOSFETs via controlled proton irradiation. The number of detected TV2a spins was estimated to be ∼105. We also found that the charge state of the TV2a spin defect can be controlled by varying the gate voltage applied to the MOSFET. [ABSTRACT FROM AUTHOR]

We systematically characterized gallium nitride (GaN) metal-oxide semiconductor interfaces formed on trench sidewalls, paying particular attention to eliminating the parasitic capacitance caused by the trench bottom. The flatband voltage (Vfb) was found to be clearly higher on the m-face trench than on the a-face trench, and an interface state density of ∼1 × 1011 cm−2 eV−1 near the conduction band edge was achieved, irrespective of the trench direction. For trench sidewalls treated with a tetramethyl ammonium hydroxide (TMAH) solution, variation in Vfb among the trench direction was suppressed, reflecting that microscopic m-faces were generated after the TMAH treatment, irrespective of the direction of the trench. Therefore, the origin of the Vfb variation was attributed to the GaN crystal face dependence of fixed charge density at SiO2/GaN interfaces. [ABSTRACT FROM AUTHOR]

This study examines the impact of the different diode characteristics on the magnetic hysteretic and iron loss properties of a conventional non-oriented (NO) silicon steel sheet core under silicon carbide (SiC) inverter excitation. We compared the magnetic properties of the magnetic core excited by the inverter using the developed Schottky barrier diode (SBD) wall-integrated trench MOSFET (SWITCH–MOS), which has a low on-voltage Von diode, with those excited by the inverter using a conventional U-shaped trench gate MOSFET (UMOS), which has a body PiN diode with high Von. This study shows for the first time that the shape of the minor loop and iron loss properties depends strongly on only the diode characteristics in the inverter. The iron loss of magnetic materials excited by the SWITCH–MOS inverter with the low-Von diode (i.e., the built-in SBD) was less than that in the case of using the conventional UMOS with a high-Von diode (i.e., the body PiN diode). That is, the SWITCH–MOS with built-in SBD can reduce not only the switching loss, but also the iron loss in magnetic materials such as motor cores. [ABSTRACT FROM AUTHOR]

Although the channel resistance is partially reduced by suppressing 4H–SiC/SiO2 interface trapping, interface scattering still presents a problem. To clearly extract the effective-field (Eeff) dependence of the dominant scattering, a body biasing technique was adopted, under the condition that the charge density is constant to fix the screening effect. The electron mobilities were observed to be several fold higher for a-, m-, and 0 3 ¯ 3 8 ¯ faces than for Si- and C-faces. This result is primarily due to a magnitude difference in the Eeff-dependent scattering; thus, the difference is emphasized at higher Eeff values. Physical parameters to reproduce the observed mobility were estimated by simulating Coulomb and roughness scattering. [ABSTRACT FROM AUTHOR]

To enhance the performance of 4H-SiC switching devices associated with power electronics, a decrease in the resistivity of the inversion channel at the SiO2/4H-SiC interface is required. It is necessary to increase the free carrier density by eliminating interface traps as well as to increase the free carrier mobility by eliminating interface scattering centers. However, the origin of the dominant scattering centers has not yet been clarified, and its scattering mechanism has not yet been experimentally investigated. Thus, in this study, the dominant scattering mechanism in the inversion channel formed on the m- and a-faces of 4H-SiC by nitridation was studied. To characterize the electron scattering in the inversion channel, temperature dependences of both the Hall effect mobility and the Hall scattering factor (γs) were investigated. Because the interface traps prevent the accurate estimation of the free carrier density by conventional capacitance measurements, evaluating γs for the SiO2/4H-SiC interface requires different approaches. Therefore, we developed and applied the "γsdα method" for regions in which the effect of the interface traps can be ignored. By experimentally observing the temperature dependent change of γs for the interface, it was revealed that the dominant scattering mechanism is Coulomb scattering. The possible origins of the mobility-limiting Coulomb scattering at the interface are discussed, including the ionized impurities in the substrate, trapped electrons at the interface, and potential fluctuations at the 4H-SiC surface. [ABSTRACT FROM AUTHOR]

The phonon-limited mobility in 4H-silicon carbide (SiC) inversion channels was precisely evaluated by employing ultralow net doping concentrations. The measured mobility in the inversion channels of these samples was comparable to the electron mobility in bulk 4H-SiC, and the temperature dependence indicated that the mobility can be ascribed to phonon-scattering-limited mobility. The strong dependence of the mobility on the net doping concentration cannot be explained by Coulomb scattering by dopant impurities. This indicates the existence of scattering origins at the SiO2/SiC interface. Comparison of dry oxidized samples and samples subjected to postoxidation annealing in nitric oxide revealed that the scattering origins were not attributable to trapped electrons at the SiO2/SiC interface states, although the nature of the scattering origins remains unclear. [ABSTRACT FROM AUTHOR]

Improved performance in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) by incorporating Ba into insulator/SiC interfaces was investigated by using a combination of the Hall effect and split capacitance-voltage measurements. It was found that a moderate annealing temperature causes negligible metal-enhanced oxidation, which is rather beneficial for increments in field-effect mobility (μFE) of the FETs together with suppressed surface roughness of the gate oxides. The combined method revealed that, while severe μFE degradation in SiC-MOSFETs is caused by a reduction of effective mobile carriers due to carrier trapping at the SiO2/SiC interfaces, Ba incorporation into the interface significantly increases mobile carrier density with greater impact than the widely-used nitrided interfaces. [ABSTRACT FROM AUTHOR]

Background and Aim The aim of the present study was to evaluate the efficacy and safety of sedation with a combination of propofol (PF) and dexmedetomidine (DEX) compared with sedation with benzodiazepines in esophageal endoscopic submucosal dissection (ESD). Methods We retrospectively reviewed clinical data for 40 consecutive patients who had undergone esophageal ESD at the Yokohama City University Hospital between July 2012 and August 2014. Of these patients, 20 were sedated with benzodiazepines (conventional group) and another 20 patients were sedated with a combination of PF and DEX (combination group). Parameters for efficacy and safety of sedation were evaluated by comparisons between the two groups. Results Median procedural times in the combination group were shorter than those in the conventional group (61 min vs 89 min, P = 0.03), and the percentage of patients who showed restlessness in the combination group was significantly lower than that in the conventional group (25% vs 65%, P = 0.025). Incidences of hypotension and bradycardia in the combination group were higher than those in the conventional group (60% vs 15%, P = 0.008, and 60% vs 15%, P = 0.008, respectively). Conclusion This retrospective study suggests that a combination of PF and DEX may provide stable deep sedation with less body movement than benzodiazepines during esophageal ESD. [ABSTRACT FROM AUTHOR]

Ultrahigh-voltage silicon carbide (SiC) devices [p-i-n diodes and insulated-gate bipolar transistors (IGBTs)] and switching test have been investigated. As a result, we have succeeded in developing a 13-kV p-i-n diode, 15-kV p-channel IGBT, and 16-kV flip-type n-channel implantation and epitaxial IGBT with a low differential specific on-resistance (R diff,on ). It was revealed that a power module fabricated using a nanotech resin, Si3N4 ceramic substrate, and W base plate was suitable for ultrahigh voltage and high temperature. A switching test was carried out using a clamped inductive load circuit, which indicated that the energy loss of a circuit with ultrahigh-voltage SiC devices is lower than that of Si devices. [ABSTRACT FROM AUTHOR]

Scleroderma and eosinophilia often occur together, though the pathogenesis is unclear. We investigated the effect of olopatadine hydrochloride in a series of cases of limited scleroderma (LS). Ten patients with LS and positive eosinophil counts (LSE) were enrolled (average age, 85 years; six men and four women). Serum concentrations of the anti-Scl-70 antibody were positive. Olopatadine hydrochloride was prescribed at 10 mg/day for 3 weeks. Serum concentrations of the anti-Scl-70 antibody significantly decreased, but changes in eosinophil numbers and percentages in peripheral blood were not significant. Factor analysis suggested a correlation between serum concentrations of the anti-Scl-70 antibody and complement C4. Olopatadine could be effective in reducing anti-Scl-70 antibodies in the elderly with LSE. [ABSTRACT FROM AUTHOR]