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A novel process is developed for minority carrier lifetime enhancement in ultra-high 4H-SiC PiN diodes. It comprises two separate processes. Firstly, the ultra-thick epitaxial grown drift layer (200μm) covered with a protective thin carbon film is subject to a 1500°C high-temperature anneal process in Ar atmosphere for 2 hours. Secondly, a surface passivation process is adopted to reduce the surface recombination rate. μ-PCD tests show that after high-temperature anneal, the thick drift layer shows a minority carrier lifetime increase to about 1.6 μs. PiN diodes based on the novel process are fabricated and their electric characteristics are measured. Results show a low specific on-resistance of 16.3 mΩ·cm2 at 25°C and 14 mΩ·cm2 at 125 °C. Compared with simulation results, it is shown that its effective minority carrier lifetime increase to about 5μs .Our study demonstrates that the developed novel process is effective in minority carrier lifetime enhancement in ultra-voltage 4H-SiC PiN diodes.

Designed for 6500V 4H-SiC JBS diodes, a highly-efficient termination structure of a non-uniform multiple floating field limiting rings (MFFLR) featuring with a non-uniform ring spacing and a multiple region division is studied and purposed. For each region, ring spacing is modulated independently by a multiplication factor and a linear increment factor. The non-uniform MFFLR structure is simulated and optimized for a better electric field distribution and a higher breakdown voltage. Based on the simulation results, 4H-SiC JBS diodes with the optimized non-uniform termination designs are fabricated. Experimental results show that the SiC JBS diode with optimized non-uniform MFFLR termination structure can achieve a breakdown voltage of up to 7800 V, and its termination efficiency is about 94% of an ideal parallel-plane junction’s. Our results demonstrate that the optimized non-uniform MFFLR termination structure is capable for SiC JBS diodes with breakdown voltage of 6500V and above. Our results can provide a valuable design methodology of edge termination structures for other high-voltage SiC devices.

In this paper, SiC MOS capacitors were fabricated and annealed in Ar/O2 = 9:1 ambient with different temperature, and the annealing effects on the reliability and performance of SiC MOS capacitance were investigated. We found that annealing in Ar/O2 ambient is capable to improve the reliability of gate oxide. When annealing in higher temperature, defects near SiO2/SiC interface are reduced, but the gate reliability deteriorated. It is difficult to obtain the best performance and reliability under the same conditions. There is a trade-off between Dit and reliability to adjust the annealing conditions.

The effect of the field oxidation process on the electrical characteristics of 6500V 4H-SiC JBS diodes is studied. The oxide thickness and field plate length have an effect on the reverse breakdown voltage of the SiC JBS diode. According the simulation results, we choose the optimal thickness of the oxide layer and field plate length of the SiC JBS diode. Two different field oxide deposition processes, which are plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LPCVD), are compared in our paper. When the reverse voltage is 6600V, the reverse leakage current of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 0.7 μA, which is 60% lower than that of PECVD process. When the forward current is 25 A, the forward voltage of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 3.75 V, which is 10% higher than that of PECVD process. There should be a trade-off between the forward and reverse characteristics in the actual high power and high temperature applications.

Background: Granulomatosis with polyangiitis (GPA) is a rare systemic autoimmune vasculitis disease that is highly correlated with antineutrophil cytoplasmic antibodies (ANCAs).It used to be called"Wegener's granulomatosis". The clinical manifestations are diverse, mainly involving the upper respiratory tract, lungs and kidneys, and this disease can involve the brain parenchyma as an isolated solid mass. Only one case has been reported thus far. To provide further information on this rare case, we report a case of granulomatous polyangiitis involving the fourth ventricle and review the relevant literature.Case characteristics: A 32-year-old Chinese female developed fever, cough, and shortness of breath for 20 days. An 8*8 cm skin ulcer was seen on the right lower limb. CT showed multiple large patches of increased density in both lungs. The patient’s serological anti-neutrophil cytoplasmic antibody cANCA was positive. Later, the patient developed dizziness and a headache. Magnetic resonance imaging of the head showed a mass of approximately 21x24 mm2 in the fourth ventricle. The patient had a craniotomy for mass resection, and macroscopically, the mass was gray–red and measured 2.5x2x2 cm and was soft, had local hemorrhage and necrosis, and had no capsule. The main microscopic features included necrotizing granulomatous vasculitis, the patient’s immunohistochemistry was positive for CD68 and negative for GFAP, and the acid-fast staining and hexaamine silver staining were negative. Combined with the clinical history, serology, and imaging, the pathological diagnosis was GPA in the fourth ventricle. The patient was switched to rituximab combined with steroid therapy because she did not tolerate cyclophosphamide. After 5 months of follow-up, the patient’s lung lesions and skin ulcers had completely improved, but the brain lesions had further progressed.Conclusion: When a patient has multiple system diseases, abnormal clinical manifestations, and positive serological ANCAs, a diagnosis of GPA should be carefully considered, and biopsies of easy-to-access sites should be performed. If the patient’s histopathological manifestations include necrotizing granulomatous vasculitis, a diagnosis of GPA is more likely. If a patient subsequently develops an intraventricular mass, the clinicians should consider a diagnosis of GPA, which can rarely involve the cerebral ventricle to avoid an unnecessary biopsy or surgical treatment of intracranial lesions. When a patient is intolerant to the traditional treatment drug cyclophosphamide and needs to be switched to rituximab, the treatment effect of intracerebral lesions is not ideal; therefore, the treatment of lesions involving GPA in the ventricle is worthy of further exploration.

In this paper, an optimized p+ shielding 4H-SiC trench-gate metal-oxide-semiconductor field effect transistors (UMOSFETs) structure with floating regions is proposed. The p+ shielding region is moved down to gain a low device on-resistance and the floating regions are designed to improve the breakdown voltage in the proposed structure. Specific on-resistances of the proposed 4H-SiC UMOSFETs is 2.62 mΩ.cm2 at VGS=18 V and VDS=10 V, compared with 4.77 mΩ.cm2 for the conventional p+ shielding UMOSFETs structure with same breakdown voltage. The on-resistance and figure of merit (FOM = VBR2/Ron) improve by 45.1% and 94.2%, respectively.

In this paper, an improved 4H-SiC trench-gate metal-oxide-semiconductor field effect transistors (UMOSFETs) structure with low on-resistance and reduced gate charge is proposed. The added n-type region in the improved structure reduces on-resistance of the device significantly while maintaining same breakdown voltage. The gate of the improved structure is designed as a p-n junction to reduce the gate-charge. The specific on-resistances of the improved 4H-SiC UMOSFETs is 1.87 mΩ.cm2 at VGS=18 V and VDS=10 V, compared with 4.48 mΩ.cm2 for the conventional p+ shielding UMOSFETs structure with same breakdown voltage. The on-resistance and figure of merit (FOM = VBR2/Ron) improve by 58.3% and 103.6%, respectively. Compared with the conventional structure, the results show that gate-drain charge of the improved structure can be improved by 23.8%.

Research has identified that epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) possess large benefits for adenocarcinoma (ADC), although little benefit for squamous cell carcinoma (SCC). The aim of the present study was to investigate the percentage of patients with SCC with the EGFR mutations subset and the benefits of EGFR TKIs in SCC. In the present study, the EGFR mutations subset was detected with an amplification refractory mutation system in 1,359 clinical SCC tissues. The association of the EGFR mutations subset with clinicopathological parameters was evaluated using the Mann-Whitney U test, and Kruskal-Wallis H. Kaplan-Meier survival analysis was used to estimate the effect of the EGFR mutations subset on SCC patient survival rates. A total of 94 out of 1,359 SCC patients were identified as having EGFR mutations, an EGFR mutation rate of 6.92%. The EGFR mutations subset in the 94 cases was identified as follows: 37.2% (35/94) in exon 19; 39.4% (37/94) in L858R; 5.3% (5/94) in T790M; 4.3% (4/94) in G719X; 2.1% (2/94) in L861Q; and 11.7% (11/94) in other mutations. Kaplan-Meier survival analysis identified that the differentiation, pathological tumor, node, metastasis stage, lymph node metastasis and distant metastases were significantly associated with patients' survival (P>0.05; log-rank test), and no significant difference was observed between TKI therapy and chemotherapy in terms of patient survival rates (P>0.05). In addition, the overall discordant rate of the EGFR mutations subset in SCC patients was relatively low. Due to the non-significant difference between TKI therapy and chemotherapy in terms of patient survival and the lower discordance rate of the EGFR mutations subset in SCC patients, EGFR TKIs could be a recommended treatment for SCC.

Objective To observe the clinical characteristics,dialysis modalities,and outcomes of end stage renal disease(ESRD)patients with polycystic kidney disease(PKD)and to evaluate the feasibility of peritoneal dialysis in these population. Methods The clinical data of ESRD patient whose primary diagnosis was PKD in Peking Union Medical College Hospital were retrospectively collected from January 1993 to December 2015.PKD patients were divided into two groups according to dialysis modality,namely peritoneal dialysis group(PKD-PD)group and hemodialysis(PKD-HD)group.In addition,we randomly chose non-PKD patients from 622 peritoneal dialysis patients who were matched with PKD-PD patients in age,gender and dialysis time.The primary end point was death.The survival rate was calculated by Kaplan-Meier analysis and the risk factors for suivival were analyzed by Cox regression model. Results Totally 47 PKD patients were enrolled,including 33 patients in PKD-PD group and 14 patients in PKD-HD group,and 42 non-PKD patients as the control group.The average age of PKD patients was(53±11)years,of which 38.3% were women.When compared with PKD-HD group,no significant difference in age,gender,comorbidities,kidney size,and residual glomerular filtration rate were observed in PKD-PD patients at baseline(all P0.05).The average time on dialysis of PKD-PD patients was(36.2±33.1)months.The weekly urea clearance index(Kt/V)and weekly creatinine clearance were similar to non-PKD-PD group at 3 months,1 year,3 years,and 5 years(all P0.05).The peritonitis rate was 1 episode/84.5 months.The survival rates at 1 year,3 years,and 5 years of PKD-PD group were 85.7%,78.6%,and 78.6%,which were similar to non-PKD-PD group and PKD-HD group respectively(all P0.05).Multivariate Cox regression analysis showed that neither PKD nor PD independently predicted the mortality. Conclusion PD can be an option for ESRD patients with PKD.目的观察成人多囊肾(PKD)终末期肾病(ESRD)患者的临床指标、透析方式和结局,评价PKD导致ESRD患者接受长期腹膜透析治疗的可行性。方法回顾性收集1993年1月至2015年12月北京协和医院确诊PKD的ESRD患者的临床资料,根据透析方式分为腹膜透析(PKD-PD)组、血液透析(PKD-HD)组,从622例腹膜透析患者中以1∶3选择年龄、性别、开始透析时间与PKD-PD组匹配的非PKD腹膜透析患者作为对照(非PKD-PD组)。以死亡为主要终点事件,利用Kaplan-Meier计算生存率,利用Cox回归模型分析影响患者生存的危险因素。结果共47例PKD患者,包括PKD-PD组33例、PKD-HD组14例,纳入非PKD-PD患者42例作为对照。PKD患者平均年龄(53±11)岁,其中女性患者18例(38.3%)。PKD-PD组与PKD-HD组患者开始透析时年龄、性别、合并症、肾脏大小、残肾功能等差异无统计学意义(

LaxHfyO nanolaminated thin film deposited using atomic layer deposition process has been studied as a high-K gate dielectric in 4H-SiC MOS capacitors. The electrical and nano-laminated film characteristics were studied with increasing post deposition annealing (PDA) in N2O ambient. The result shows that high quality LaxHfyO nano-laminated thin films with good interface and bulk qualities are fabricated using high PDA temperature.

It has been reported that CREPT acts as a highly expressed oncogene in a variety of tumors, affecting cyclin D1 signal pathways. However, the distribution and clinical significance of CREPT in NSCLC remains poorly understood. Our study focused on the role of CREPT on the regulation ofnon-small cell lung cancer (NSCLC). We found that CREPT mRNA and protein expression was significantly increased in NSCLC compared with adjacent lung tissues and was increased in various NSCLC cell lines compared with the normal human bronchial epithelial (HBE) cell line. siRNA-induced knockingdown of CREPT significantly inhibited the proliferation and migration of NSCLC cell lines by arresting cell cycle in S phase. Moreover, CREPT knocking down affected the expression of cell cycle proteins including c-mycand CDC25A. Finally, we found there were obvious correlations between CREPT with c-myc expression in histological type, differentiation, and pTNM stages of NSCLC (P0.3). Immunohistofluorescence studies demonstrated a co-localization phenomenon when CREPT and c-myc were expressed. Thus, we propose that CREPT may promote NSCLC cell growth and migration through the c-myc and CDC25A signaling molecules.