The improvement of an mc-Si solar cell through reverse bias and high temperature (BT) aging was investigated using laser beam-induced current (LBIC) and electroluminescence (EL) techniques. We demonstrated that the dark current of the cell decreased with increasing aging time, which led to an increase in the maximum power after BT aging. The improvement in the maximum power was presumed to be due to a reduction in the shunt current in the equivalent circuit model, and we found that the recombination centers in the vicinity of the surface decreased with BT aging. Applying a reverse bias and a high temperature successfully improved the solar cells.

SiC-MOSFETs with high reliability have been desired for electric vehicles. We classify commercial SiC-MOSFETs into “heavily nitrided” and “lightly nitrided” based on time-dependent gate-current characteristics of fabricated devices. In “heavily nitrided” devices for higher mobility, high-voltage gate pulse for screening of B-mode (extrinsic defects) causes hole-trapping near the SiO2/SiC interface through impact ionization. This phenomenon leads to an increase in gate current as well as a negative shift of threshold voltage. Moreover, this is enhanced at low temperatures (-60, 25°C). Thus, high-temperature (200°C) screening is preferable. In addition, the relation between Weibull slopes for time-to-breakdown and charge-to-breakdown is closely examined.

It has been reported that the combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, and an immune checkpoint inhibitor enhances the antitumor activity via tumor immune modulation, and clinical trials of the combination have also been conducted. However, the changes of immuno-oncologic features by lenvatinib are poorly understood clinically. Here we show the effects of lenvatinib on immune status for optimizing the combination therapy in hepatocellular carcinoma (HCC) using clinical samples.

Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) have been produced by several vendors for commercial applications. SiC-MOSFET reliability was assessed using bias-temperature instability (BTI) and time-dependent dielectric breakdown (TDDB) characteristics. Here, we compared two planar SiC-MOSFET samples (A and B) from different vendors. The samples exhibited significantly different positive and negative BTI, time-dependent gate-current, TDDB lifetime statistics, and temperature dependence. These differences suggest NO (nitric oxide)-annealing variations.

Silicon-carbide metal-oxide-semiconductor field-effect transistors (SiC-MOSFETs) are core devices for future power electronics. The factors limiting their automotive applications are currently under investigation. Postoxidation annealing in NO gas is a key technology to achieving high carrier mobility in SiC-MOSFETs. In this article, we study the NO annealing effects on time-dependent dielectric breakdown (TDDB) reliability by the constant voltage stress (CVS) method at room temperature (RT). We show that heavy NO annealing enhances hole trapping near the SiO2/SiC interface and leads to a rapid increase in the gate current (I-g) and results in shorter time-to-breakdown (t(BD)) and smaller Weibull slope of t(BD) in comparison to light NO annealing case. However, the detailed examination of the I-g behavior reveals that the charge-to-breakdown (Q(BD)) and its distribution do not deteriorate. Therefore, we must reconsider the use of the CVS method by examining the I-g behavior during stress, which strongly depends on NO annealing conditions.

Gate oxide integrity (GOI) are the most important concern in automotive applications of SiC-metal-oxide-semiconductor field-effect transistors (MOSFETs). As well as for the so-called B-mode defect density reduction, the time-dependent dielectric breakdown (TDDB) mechanism including the B-mode should be clarified in comparison to Si-MOSFETs. We have reported an anomalous behavior in the form of a continuous increase in the gate current during a Fowler-Nordheim stress test of commercially available SiC-MOSFETs, which we attributed to hole trapping near the SiO2/SiC interface. In this paper, the impact of this phenomenon on the TDDB lifetime is investigated, and the effects of AC on the TDDB lifetime enhancement in SiC-MOSFET under gate-switching operations (1 kHz and 100 kHz, at room temperature) are reported.

Positive bias temperature instability (PBTI) is one of the crucial issues in SiC-MOSFETs’ introduction to automotive applications. We have investigated PBTI of commercially available SiC-MOSFETs under gate-switching operation to consider real power circuits operation. The use of negative gate off-voltage ( V gs (OFF) ~ -5 V) is shown to suppress V th shift (Δ V th ) under 100 kHz gate-switching operation. This gate voltage corresponds to the flat band condition, under which the electrons trapped by the near-interfacial traps are effectively detrapped through the interface states around the conduction band edge.

The interior and surface degradation of a multicrystalline silicon (mc-Si) solar cell module was investigated using the laser beam-induced current (LBIC) technique. Reverse voltage was applied to avoid the influence of the solar cells not irradiated with light and to evaluate the LBIC intensity only of the illuminated solar cell. In addition, we found that the mc-Si, but not the solar cell surface, is comprised of homogeneous crystals and the degraded layer is estimated to be $\sim 0.6~\mu\text{m}$ . The LBIC technique was applied at several wavelengths under reverse bias conditions in order to analyze degraded solar cells.

Despite the advances in SiC-MOSFET technology in recent years, high-temperature stability remains a significant issue. In this work, we examine the positive bias temperature instability of SiC-MOSFETs induced by gate-switching operation (AC-PBTI). The dependence of the threshold voltage shift (ΔVth) on the duty-cycle of gate pulses (1 kHz) is measured, which shows a strong dependence on the gate off-voltage Vgs(OFF). When using Vgs(OFF) = −5 V, ΔVth becomes negligible even in a 90% duty cycle, which is practically informative for power circuit applications. The trap–detrap model for Si is used to explain this marked behavior. Finally, by considering the band bending at Vgs(OFF), we propose the interface-state-assisted detrapping mechanism as one possible explanation for this behavior.

SiC-MOSFETs have been markedly developed, and the main issues remaining are high-temperature stability and gate-oxide integrity. In this paper, we report special features of I-ds-V-gs and I-g-V-gs characteristics of commercially available SiC-MOSFETs during high-gate-voltage and high-temperature stress. Moreover, we introduce simple analytical models that reveal the effects of the trapped charges on the characteristics. Interface states around the conduction-band edge are suggested to be the key mechanisms of Fowler-Nordheim stress degradation (FN degradation) as well as negative bias temperature instability (NBTI), which affects both mobility and carrier density. Hole trapping is also important in FN degradation as well as NBTI. Near-interfacial electron trapping and detrapping found in positive bias temperature instability (PBTI) is also observed in FN degradation. A continuous I-g increase during FN stress, which is the most specific to SiC-MOSFETs, is related to the observation that near-interfacial electron trapping has little effect on FN tunneling. (C) 2016 The Japan Society of Applied Physics

SiC-MOSFETs have been remarkably developed in recent years, and the main remaining issue is reliability such as high temperature stability and gate oxide integrity. In this presentation, we report some special features observed in I-V characteristics of commercially available SiC-MOSFETs during high voltage and temperature stress. Interface states around conduction band edge and hole-trapping and near-interfacial electron-trapping are suggested to be the key mechanisms in stress degradation when compared with the conventional Si-MOSFETs. In particular, a continuous Ig increase in MOS structure during stress is found for the first time.

Treatment success of chronic hepatitis C virus genotype 1 infection has improved with the advent of telaprevir plus peg-interferon/ribavirin triple combination therapy. However, the effect of inosine triphosphatase (ITPA) polymorphism on dose reduction during triple therapy, especially during the postmarketing phase, has not been sufficiently evaluated. We analysed 273 patients with genotype 1 infection who were treated with triple therapy and assessed the effect of the ITPA polymorphism on dose reduction. ITPA and IFNL4 SNP genotypes were determined by the Invader assay. A stepwise multivariate regression analysis was performed to identify factors associated with outcome of the therapy. The overall sustained viral response (SVR) rate 12 weeks after the end of therapy was 80.2% (219/273). Decline of haemoglobin was significantly faster, and ribavirin was more extensively reduced in patients with ITPA SNP rs1127354 genotype CC than CA/AA. Extensive reduction of ribavirin resulted in mild reduction of telaprevir and peg-interferon, but no significant increase in viral breakthrough. Although the amount of telaprevir given was slightly higher in CA/AA patients, the total dose of peg-interferon and the SVR rate did not differ between the two groups. Multivariate analysis showed that IFNL4 but not ITPA SNP genotype, platelet count and peg-interferon adherence were significantly associated with outcome of therapy. Postmarketing-phase triple therapy resulted in a high SVR rate in spite of extensive ribavirin dose reduction in a diverse patient population, indicating the importance of treatment continuation and appropriate management of adverse events.