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Background Anastomotic leak (AL) is a common but severe complication after oesophagectomy. It is unknown how to determine the severity of AL objectively at diagnosis. Determining leak severity may guide treatment decisions and improve future research. This study aimed to identify leak-related prognostic factors for mortality, and to develop a Severity of oEsophageal Anastomotic Leak (SEAL) score. Methods This international, retrospective cohort study in 71 centres worldwide included patients with AL after oesophagectomy between 2011 and 2019. The primary endpoint was 90-day mortality. Leak-related prognostic factors were identified after adjusting for confounders and were included in multivariable logistic regression to develop the SEAL score. Four classes of leak severity (mild, moderate, severe, and critical) were defined based on the risk of 90-day mortality, and the score was validated internally. Results Some 1509 patients with AL were included and the 90-day mortality rate was 11.7 per cent. Twelve leak-related prognostic factors were included in the SEAL score. The score showed good calibration and discrimination (c-index 0.77, 95 per cent c.i. 0.73 to 0.81). Higher classes of leak severity graded by the SEAL score were associated with a significant increase in duration of ICU stay, healing time, Comprehensive Complication Index score, and Esophagectomy Complications Consensus Group classification. Conclusion The SEAL score grades leak severity into four classes by combining 12 leak-related predictors and can be used to the assess severity of AL after oesophagectomy.

Hepatobiliary and pancreatic surgery is frequently complicated by surgical site infections (SSI) with significant postoperative morbidity and mortality rates contributing to the economic burden on healthcare. Advancements in operative techniques to prevent SSI are gaining traction in clinical practice. This study compares the effectiveness of the 'loop and drain technique (LDT)', a combination method utilizing a continuous subcutaneous vessel loop and subcuticular suture for surgical wound closure in patients undergoing upper gastrointestinal surgery at a Metropolitan Hospital in Sydney.A retrospective review of patients who underwent an upper gastrointestinal procedure was conducted at Bankstown-Lidcombe hospital between 2017 and 2019. There were 77 patients in the LDT group and 123 patients included in the control group. The primary outcome assessed was the rate of SSI. Secondary outcomes included length of stay (LOS) and drainage of surgical site infections.Two hundred adult patients were treated for an upper gastrointestinal procedure. The most common operation was a Whipple procedure (35.0%). The rate of SSI was 12.5% with all these patients receiving intravenous antibiotics. The LDT cohort had a significantly lower rate of SSI compared to their counterparts (3.9% vs. 17.9%, P = 0.004).The LDT method is associated with a decreased incidence of SSI and should be considered as a cost-effective operative technique to improve patient outcomes after upper gastrointestinal surgery.

BACKGROUND: The global burden of pancreatic cancer has steadily increased, while the prognosis after pancreatic cancer diagnosis remains poor. This study aims to compare the stage- and age-specific pancreatic cancer net survival (NS) for seven high-income countries: Australia, Canada, Denmark, Ireland, New Zealand, Norway, and United Kingdom. METHODS: The study included over 35,000 pancreatic cancer cases diagnosed during 2012–2014, followed through 31 December 2015. The stage- and age-specific NS were calculated using the Pohar-Perme estimator. RESULTS: Pancreatic cancer survival estimates were low across all 7 countries, with 1-year NS ranging from 21.1% in New Zealand to 30.9% in Australia, and 3-year NS from 6.6% in the UK to 10.9% in Australia. Most pancreatic cancers were diagnosed with distant stage, ranging from 53.9% in Ireland to 83.3% in New Zealand. While survival differences were evident between countries across all stage categories at one year after diagnosis, this survival advantage diminished, particularly in cases with distant stage. CONCLUSION: This study demonstrated the importance of stage and age at diagnosis in pancreatic cancer survival. Although progress has been made in improving pancreatic cancer prognosis, the disease is highly fatal and will remain so without major breakthroughs in the early diagnosis and management.

Introduction: Diabetes is a recognised risk for several chronic and acute illnesses, including increased complications in surgery for oesophageal cancer. Our primary aim is to determine the impact of diabetes on postoperative surgical and medical complications after oesophagectomy. Methods: All oesophagectomies for malignancy as reflected in the 2016-2018 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) datasets were extracted and analysed. Current Procedural Terminology (CPT) codes used were 1) open procedures (43107, 43108, 43112, 43113, 43116, 43117, 43118, 43121, 43122, and 43123) and 2) hybrid procedures (43186, 43287, and 43288). Logistic regression models examined associations between diabetic status and adverse outcomes. The associations were adjusted for sex, race, age group, operation year, CPT code, body mass index (BMI), smoking, congestive heart failure, antihypertensives, renal failure, and dyspnoea. Results: Two thousand five hundred and thirty-eight oesophagectomies were identified. 86.45% (n=2,194) underwent open procedures and 13.55% (n=344) had hybrid procedures. There were 177 insulin-dependent diabetics (IDDM) and 320 (12.61%) non-insulin-dependent diabetics (NIDDM). 84.14% were male and 77.74% were Caucasian. 89.48% of the patients were between 50 and 79 years of age. 40.27% experienced postoperative complications. Medical complications (odds ratio [OR]: 1.7, p-value: 0.002), surgical complications (OR: 1.9, p-value

Laparoscopic fundoplication (LF) is well-established as the surgical intervention of choice for management of refactory gastro-esophageal reflux disease. Much of its success lies in the reported benefits in symptom control outlined by the postoperative patient. It is unclear whether patient-reported outcomes differ according to the institution type providing care. This review aimed to address this knowledge gap by reviewing the available evidence examining patient-reported outcomes of LF in non-metropolitan centers.To investigate patient-reported outcomes of LF performed in regional or community-based hospitals.Four electronic databases, and citations of relevant articles.Only studies that separately reported patient-reported outcomes of LF performed in regional or community hospitals were included; papers deemed to be unclear about the type of facility in which LF surgeries were performed, or in which data from LF surgeries performed in regional/community hospitals was combined with data from major metropolitan hospitals, were excluded.Only studies that were graded as fair or good using Quality Assessment Tool for Observational Cohort and Cross-sectional studies were eligible for inclusion in this review. Seven studies were then eligible for inclusion, all of which were observational cohort studies with 6 of the studies reporting on a single intervention arm.Seven observational cohort studies were included in the review, with a combined total of 1071 patients who underwent LF at non-metropolitan centers. Of these, data was collected for 742 patients, yielding an overall response rate of 69.3%. All 7 studies assessed patients' post-operative outcomes through questionnaires that were based on a modified Likert scale or a similar tool. Overall patient satisfaction was high (86%) and a significant majority of patients stated they would recommend the procedure to others (93.3%). Post-operative prevalence of reflux and dysphagia compared favorably to rates generally reported in the literature (11.9% and 17.6% respectively). Further research is required to ascertain the safety of performing these procedures in non-metropolitan hospitals.Current evidence suggests that patient-reported outcomes are favorable for patients undergoing LF in community settings, and are broadly comparable to those undergoing LF in tertiary-level centers.

The prognostic role of neutrophil to lymphocyte ratio (NLR) has been explored extensively in the literature. The aim of this meta-analysis was to evaluate the link between NLR and lymph node metastasis in gastric cancer. A method for increasing specificity and sensitivity of pre-treatment staging has implications on treatment algorithms and survival.The relevant databases were searched as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart. After selection, 12 full text articles that met the inclusion criteria were included for quantitative analysis. 2 × 2 squares were generated using lymph node positive/negative, and NLR high/low data. The effect size for each study was calculated using the DerSimonian-Laird random effects model. P values were calculated using the chi-square method. Finally publication bias was evaluated. All statistics were calculated using R Studio.Meta-analysis showed a 1.90 times (odds ratio, with 95% CI 1.52-2.38) increase in risk of positive lymph node status with high neutrophil to lymphocyte ratio. This has significant implications for cancer screening and staging, as NLR is a highly reproducible, cost-effective, and widely available prognostic factor for gastric cancer patients. Additionally, high or low NLR values may have implications for management pathways. Patients with lymph node metastasis can be offered neoadjuvant chemotherapy, avoiding salvage therapy in the form of adjuvant chemoradiotherapy, which is poorly tolerated.This meta-analysis shows an association between NLR and positive lymph node status in gastric cancer patients with implications for staging, as well as preoperative personalisation of therapy.

Renal Cell Carcinoma (RCC) accounts for approximately 90% of primary renal malignancies, of which the clear cell subtype is most common. While metastatic disease is common at the time of diagnosis and generally confers a poor prognosis, metastatic RCC may demonstrate relatively indolent behaviour and present many years after resection of the primary tumour, including to the pancreas. The available literature suggested that surgical resection was appropriate for select patients, including those with a solitary pancreatic metastasis, minimal comorbidities and uncomplicated progress from initial treatment of their primary renal malignancy. A retrospective case series of patients presenting with RCC metastases to the pancreas, managed via surgical resection at a tertiary teaching hospital was reviewed. Analysis of patient demographics, investigations, management and outcomes were performed, with a focus on post-operative morbidity and overall survival. Between 2000 and 2020, 7 patients underwent pancreatic resection of RCC metastases at our tertiary teaching hospital with curative intent. Median age at time of resection was 66 years. No post-operative mortality or major morbidity was experienced by the 7 patients, although 4 patients developed some degree of pancreatic insufficiency. Four patients experienced recurrent metastatic RCC, with median time to recurrence of 3.5 years. This was the largest local study to describe an Australian experience of the surgical management of RCC pancreatic metastases. These patients are frequently afforded prolonged survival following pancreatic resection, but often develop other distant sites of disease and second renal tumours.

Background The Wnt receptors ROR1 and ROR2 are generating increased interest as cancer therapeutic targets but remain understudied in pancreatic ductal adenocarcinoma (PDAC). Compared to canonical Wnt/ β-catenin signalling, the role of noncanonical Wnt signalling in PDAC remains largely unknown. Only one study has investigated the prognostic significance of the noncanonical Wnt signalling receptor, ROR2 in PDAC. No studies have investigated the prognostic role of ROR1 in PDAC. Methods Here, we performed analysis of ROR1 and ROR2 mRNA expression in three publicly available datasets ICGC-PACA-AU (n = 81), TCGA-PAAD (n = 150) and CPTAC-PDAC (n = 137). ROR1 and ROR2 protein expression from the CPTAC-PDAC discovery cohort were also analysed. Immunohistochemistry (IHC) using the validated anti ROR1 monoclonal antibody (4A5) was performed on the Australian Pancreatic Cancer Genome Initiative (APGI) cohort of PDAC samples (n = 152). Association between ROR1 cytoplasmic staining intensity and clinicopathological parameters including stage, grade and overall survival (OS) was investigated. Results High ROR1 mRNA expression levels correlated with a favourable OS outcome in all of the ICGC-PACA-AU, TCGA-PAAD and CPTAC-PDAC cohorts. ROR1 protein expression was not associated with stage, grade or OS in the APGI cohort. Conclusion ROR1 and ROR2 have potential as prognostic markers when measured at the mRNA level in PDAC. Our IHC cohort did not support ROR1 protein expression in predicting OS, and highlighted the discrepancy of prognostic biomarkers when measured by MS, IHC and RNAseq.

This paper presents initial results on developing high temperature capable SiC JFET based IC technology. All JFET devices are fully planar, formed by ion implantation, and the device design allows the use of semi-insulating or conductive substrates. Basic analog and logic ICs were built in order to demonstrate the technology high temperature capability. All circuits used enhancement mode n-channel JFETs as active transistors, and depletion mode transistors as active loads. The logic circuits built included NOT, NAND, and NOR gates. The analog circuits built included a simple one-stage operational amplifier. JFETs and ICs were packaged in ceramic DIP packages and tested at temperatures up to 350°C, which was the IC design target maximum operating temperature.

Hydatid disease (HD) remains endemic in Australia, with estimated incidence highest in rural and indigenous populations. Its recurrence is defined by new active cysts arising after appropriate therapy, and affects anywhere between 2-25% of total cases. Available treatment options include surgical resection, percutaneous drainage, and chemotherapy. Interestingly, their individual contributions to long-term minimisation of recurrence are scarcely described in the literature. We present a unique case of a 27-year-old female with recurrent hepatic HD requiring repeat operations and long-term chemotherapy. Prevention and treatment of recurrent HD requires careful evaluation of a multitude of factors, including disease characteristics, patient attributes, physician expertise and availability of resources. Consistent long-term follow up is required to better ascertain the long-term efficacy of reported treatment modalities for preventing recurrence. Despite a growing body of research looking at treatment of HD, there remains a considerable amount of controversy regarding most effective approach for minimising and preventing its recurrence.

Aim: Overall 5-year survival for pancreatic cancer is ∼5%. Optimizing the care that pancreatic cancer patients receive may be one way of improving outcomes. The objective of this study was to establish components of care which Australian health professionals believe important to optimally manage patients with pancreatic cancer. Methods: Using a Delphi process, a multidisciplinary panel of 250 health professionals were invited to provide a list of factors they considered important for optimal care of pancreatic cancer patients. They were then asked to score and then rescore (from one [no importance/disagree] to 10 [very important/agree]) the factors. The mean and coefficient of variation scores were calculated and categorized into three levels of importance. Results: Overall, 63 (66% of those sent the final questionnaire; 25% of those initially invited) health professionals from nine disciplines completed the final scoring of 55 statements/factors encompassing themes of presentation/staging, surgery and biliary obstruction, multidisciplinary team details and oncology. Mean scores ranged from 3.7 to 9.7 with the highest related to communication and patient assessment. There was substantial intra- and interdisciplinary variation in views about MDT membership and roles. Conclusion: Overall, the opinions of Australian health professionals reflect international guideline recommended care; however, they identified a number of additional factors focusing on where patients should be treated, the importance of clear communication and the need for multidisciplinary care which were not included in current clinical practice guidelines. Differences in priorities between specialty groups were also identified.

Carbon nanotubes (CNTs) have unique thermal/electrical/mechanical properties and high aspect ratios. Growth of CNTs directly onto reactive material substrates (such as metals and carbon based foam structures, etc.) to create a micro-carbon composite layer on the surface has many advantages: possible elimination of processing steps and resistive junctions, provision of a thermally conductive transition layer between materials of varying thermal expansion coefficients, etc. Compared to growing CNTs on conventional inert substrates such as SiO2, direct growth of CNTs onto reactive substrates is significantly more challenging. Namely, control of CNT growth, structure, and morphology has proven difficult due to the diffusion of metallic catalysts into the substrate during CNT synthesis conditions. In this study, using a chemical vapor deposition method, uniform CNT layers were successfully grown on copper foil and carbon foam substrates that were pre-coated with an appropriate buffer layer such as Al2O3 or Al. SEM images indicated that growth conditions and, most notably, substrate surface pre-treatment all influence CNT growth and layer structure/morphology. The SEM images and pull-off testing results revealed that relatively strong bonding existed between the CNT layer and substrate material, and that normal interfacial adhesion (0.2‒0.5 MPa) was affected by the buffer layer thickness. Additionally, the thermal properties of the CNT/substrate structure were evaluated using a laser flash technique, which showed that the CNT layer can reduce thermal resistance when used as a thermal interface material between bonded layers.

A method of growing SiC nanowires (NWs) on 4H–SiC surfaces by in situ vapor-phase catalyst delivery was developed as an alternative to the ex situ deposition of the metal catalyst on the targeted surfaces before the NW chemical vapor deposition (CVD) growth. In the proposed method, sublimation of the catalyst from a metal source placed in the hot zone of the CVD reactor, followed by condensation of the catalyst-rich vapor on bare substrate surface was used to form the catalyst nanoparticles required for the vapor–liquid–solid (VLS) growth of SiC NWs. The NW density was found to gradually decrease downstream from the catalyst source and was influenced by both the gas flow rate and by the catalyst diffusion through the boundary layer above the catalyst source. Formation of poly-Si islands at too low value of the C/Si ratio created preferential nucleation centers for misaligned SiC NWs and NW bushes. The flexibility of controlling the nanoparticle density made this technique suitable for NW growth on horizontal surfaces as well as on patterned SiC substrates, including the vertical sidewalls of SiC mesas.

Vanadium doping from SiCl4 source during epitaxial growth with chlorinated C and Si precursors was investigated as a mean of achieving compensated and semi-insulating epitaxial 4H-SiC layers for device applications. Thin epilayers were grown at 1450°C with a growth rate of ~6 μm/h. Experiments at 1600°C resulted in the growth rates ranging from 60 to 90 µm/h producing epilayers with thickness above 30 µm. V concentrations up to about 1017cm-3 were found safe for achieving defect-free epilayer surface morphology, however certain degradation of the crystalline quality was detected by XRD at V concentrations as low as 3-5x1015 cm-3. Controllable compensation of nitrogen donors with V acceptors provided low-doped and semi-insulating epitaxial layers. Mesa isolated PiN diodes with V-acceptor-compensated n- epilayers used as drift regions showed qualitatively normal forward- and reverse-bias behavior.

Growth of SiC nanowires (NWs) on monocrystalline 4H-SiC substrates was conducted to investigate a possibility of NW alignment and polytype control. The growth directions of the NWs on the top surfaces and the vertical sidewalls of 4H-SiC mesas having different crystallographic orientations were investigated. The majority of the NWs crystallize in the 3C polytype with the growth axis. Six orientations of the 3C NWs axis with respect to the substrate were obtained simultaneously when growing on the (0001) plane. In contrast, no more than two NW axis orientations coexisted when growing on a particular mesa sidewall. Growth on a particular {10-10} plane resulted in only one NW axis orientation, giving well-aligned NWs.

Several different growth directions of SiC nanowires (NWs) determined by the substrate surface crystallographic orientation were achieved by conducting vapor−liquid−solid growth on the top surfaces and the sidewalls of the 4H-SiC mesas. When substrate- dependent (i.e., epitaxial) growth was ensured, six possible crystallo- graphic orientations of 3C-SiC NW axis with respect to the 4H-SiC substrate were realized. They all were at 20° with respect to the substrate c plane, and their projections on the c plane corresponded to one of the six equivalent ⟨101⟩ crystallographic directions. All six orientations were obtained simultaneously when growing on the (0001) top surface of the 4H-SiC wafer or on the mesa tops. In contrast, no more than two NW orientations coexisted when grown on any particular crystallographic plane of a mesa sidewall. In particular, the {101 mesa sidewall plane resulted in only one NW orientation, thereby producing well-aligned NW arrays desirable for device applications.

SiC nanowires were grown on monocrystalline 4H-SiC wafers by chemical vapor deposition using the vapor-liquid-solidgrowthmode.Thegrowthdirectionofthenanowireswasdictatedbythecrystallographicorientationofthe 4H-SiC substrates. Two distinct types of nanowires were obtained. The first type crystallized in the 3C polytype with the AE111ae nanowire axes. These nanowires grew at 20� with respect to the substratec-planes and exhibited high densities of stacking faults on those {111} planes that are parallel to the substrate c-planes. The second type featured the 4H structure albeit with a strong stacking disorder. The stacking faults in these nanowires were perpendicular to the (0001) nanowire axes. Possible growth mechanisms that led to the formation of 3C and 4H polytypes are discussed.

In this paper we report the electrical and thermal performance characteristics of 1200 V, 100 A, 200°C (Tj), SiC MOSFET power modules configured in a dual-switch topology. Each switch-diode pair was populated by 2 x 56 mm2 SiC MOSFETs and 2 x 32 mm2 SiC junction barrier Schottky (JBS) diodes providing the 100 A rating at 200°C. Static and dynamic characterization, over rated temperature and power ranges, highlights the performance potential of this technology for highly efficient drive and power conversion applications. Electrical performance comparisons were also made between SiC power modules and equivalently rated and packaged IGBT modules. Even at a modest Tj=125°C, conduction and dynamic loss evaluation for 20kHz, Id=100A operation demonstrated a significant efficiency advantage (38-43%) over the IGBT components. Initial reliability data also illustrates the potential for SiC technology to provide robust performance in harsh environments.

In this work, heavily aluminum (Al)-doped layers for ohmic contact formation to p-type SiC were produced by utilizing the high efficiency of Al incorporation during the epitaxial growth at low temperature, previously demonstrated by the authors’ group. The low-temperature halo-carbon epitaxial growth technique with in situ trimethylaluminum (TMA) doping was used. Nearly featureless epilayer morphology with an Al atomic concentration exceeding 3 × 1020 cm−3 was obtained after growth at 1300°C with a growth rate of 1.5 μm/h. Nickel transfer length method (TLM) contacts with a thin adhesion layer of titanium (Ti) were formed. Even prior to contact annealing, the as-deposited metal contacts were almost completely ohmic, with a specific contact resistance of 2 × 10−2 Ω cm2. The specific contact resistance was reduced to 6 × 10−5 Ω cm2 by employing a conventional rapid thermal anneal (RTA) at 750°C. Resistivity of the epitaxial layers better than 0.01 Ω cm was measured for an Al atomic concentration of 2.7 × 1020 cm−3.

Low-temperature halo-carbon homoepitaxial growth is suitable for selective epitaxial growth of 4H-SiC using SiO2 mask. A possibility of achieving high values of doping in combination with the selective growth makes it an alternative to ion implantation for selective doping in SiC. In this work, TMA doping in situ during a blanket low-temperature epitaxial growth was utilized to produce heavily Al doped SiC layers for Ohmic contact formation to p-type SiC. Nearly featureless epilayer morphology with Al atomic concentration exceeding 3x1020 cm-3 was obtained after growth at 13000C with the growth rate of 1.5 µm/hr. Ni TLM contacts with a thin adhesion layer of Ti were formed. The as-deposited metal contacts were almost completely Ohmic even before annealing. The specific contact resistance of 2x10-2 Ohm-cm2 and 6x10-5 Ohms-cm2 was achieved without and with contact annealing respectively. The resistivity of the epitaxial layers better than 0.01 Ohm cm was measured for Al atomic concentration of 2.7x1020 cm-3.

Despite advances in the understanding and treatment of pancreatic cancer in the last two decades, there is a persisting nihilistic attitude among clinicians. An alarmingly high rate of under-utilization of surgical management for operable pancreatic cancer was recently reported in the USA, where more than half of patients with stage 1 operable disease and no other contraindications were not offered surgery as therapy, denying this group of patients a 20% chance of long-term survival. These data indicate that a nihilistic attitude among clinicians may be a significant and reversible cause of the persisting high mortality of patients with pancreatic cancer. This article examines the modern management of pancreatic cancer, in particular, the advances in surgical care that have reduced the mortality of pancreatectomy to almost that of colonic resection, and outlines a strategy for improving outcomes for patients with pancreatic cancer now and in the future.

In this work we have demonstrated the operation of 600-V class 4H-SiC vertical-channel junction field-effect transistors (VJFETs) with 6.6-ns rise time, 7.6-ns fall time, 4.8-ns turn-on and 5.4-ns turn-off delay time at 2.5 A drain current (IDS), which corresponds to a maximum switching frequency of 41 MHz – the fastest ever reported switching of SiC JFETs to our knowledge. At IDS of 12 A, a 19.1 MHz maximum switching frequency has been also achieved. Specific on-resistance (Rsp-on) in the linear region is 2.5 m·cm2 at VGS of 3 V. The drain current density is greater than 1410 A/cm2 at 9 V drain voltage. High-temperature operation of the 4H-SiC VJFETs has also been investigated at temperatures from 25 °C to 225 °C. Changes in the on-resistance with temperature are in the range of 0.90~1.33%/°C at zero gate bias and IDS of 50 mA. The threshold voltage becomes more negative with a negative shift of 0.096~0.105%/°C with increasing temperature.

4H-SiC vertical depletion-mode trench JFETs were fabricated, packaged, and then irradiated with either 6.8 Mrad gamma from a 60Co source, a 9x1011 cm-2 dose of 4 MeV protons, or a 5x1013 cm-2 dose of 63 MeV protons. 4H-SiC Schottky diodes were also fabricated, packaged and exposed to the same irradiations. The trench VJFETs have a nominal blocking voltage of 600 V and a forward current rating of 2 A prior to irradiation. On-state and blocking I-V characteristics were measured after irradiation and compared to the pre-irradiation performance. Devices irradiated with 4 MeV proton and gamma radiation showed a slight increase in on resistance and a decrease in leakage current in blocking mode. Devices irradiated with 63 MeV protons, however, showed a dramatic decrease in forward current. DLTS measurements were performed, and the results of these measurements will be discussed as well.

An optimized multiple floating guard ring structure is investigated for the first time as an edge termination method for high voltage 4H-SiC planar devices. Simulations were performed to investigate SiC guard ring termination, and determine the optimum guard ring spacing for planar diodes with up to four floating rings. Simulated optimized designs predicted breakdown values from 40% of the ideal breakdown with a single ring, to 84% of the ideal value for diodes with four rings. Implanted 4H-SiC pn diodes with optimized guard ring designs were fabricated and results correlated to simulation. Experimental breakdown values of 1.2–1.3 kV for guard ring structure with four rings were in good agreement with simulated results.

SiC nanowires (NWs) are attractive building blocks for the next generation electronic devices since silicon carbide is a wide bandgap semiconductor with high electrical breakdown strength, radiation resistance, mechanical strength, thermal conductivity, chemical stability and biocompatibility. Epitaxial growth using metal-catalyst-based vapor-liquid-solid mechanism was employed for SiC NW growth in this work. 4H-SiC substrates having different crystallographic orientations were used in order to control NW alignment and polytype. A new technique based on vapor-phase delivery of the metal catalyst was developed to facilitate control of the NW density. Both 4H and 3C polytypes with a strong stacking disorder were obtained. The 4H and 3C NWs had different orientations with respect to the substrate. 4H NWs grew perpendicular to the c-plane of the substrate. The stacking faults (SFs) in these nanowires were perpendicular to the [0001] nanowire axes. All 3C NWs grew at 20° with respect to the substrate c-plane, and their projections on the c-plane corresponded to one of the six equivalent ⟨101-0⟩ crystallographic directions. All six orientations were obtained simultaneously when growing NWs on the (0001) substrate surface, while only one or two NW orientations were observed when growing NWs on any particular crystallographic plane parallel to the c-axis of the substrate. Growth on {101-0} surfaces resulted in only one NW orientation, thereby producing well-aligned NW arrays. Preliminary measurements of the NW electrical conductivity are reported utilizing two-terminal device geometry.

In this paper, we present an investigation on the different aspects of the performance of a 600V, 3A 4H-SiC vertical-trench junction field effect transistor (VJFET) at cryogenic and high temperatures. Some critical device physics related factors that affect the DC characteristics and switching performance of the device are explored. In particular, the experimental low-temperature performance of 4H-SiC VJFETs (down to 30K or -243/spl deg/C) is presented for the first time to our knowledge.

A new generation of power semiconductor devices is emerging based on the maturation of semiconducting silicon carbide. In this paper, alternatives to the divider resistors are presented using newly available 600-V, 2-A SiC JFETs. Two configurations are possible. The first employs a series combination of JFETs with shorted gate-source terminals operating as current limiting diodes. This allows a greater voltage to be blocked by the IGBT than can be blocked by currently available SiC JFETs. The superior thermal properties of SiC JFETs permit the larger bias currents required to drive the large IGBT gate capacitance at high repetition rates to be sourced. The second configuration is highly efficient and avoids thermal loading of the SiC JFET. The SiC current limiting diodes are replaced by a single SiC JFET switched concurrently with the IGBT. This configuration requires the SiC JFET to block the full voltage blocked by the IGBT, a capability expected in later generations of SiC JFETs. The gate drivers demonstrated in this paper are also applicable to power modulators using large arrays of silicon power MOSFETs. The near-term prospect for very fast SiC JFETs as replacements for silicon MOSFETs in power modulators is also discussed

An overview of silicon carbide (SiC) power device technology is given with an emphasis on processing issues and commercial applications. Schottky Barrier Diodes (SBDs) were the first to be made commercially available in 2001, with power switch and RF amplifiers soon to follow. This paper discusses the performance of current available rectifiers and published power switch development and identifies key issues in processing and device structures which have influenced past and will impact future SiC product development.

Edge termination is a critical design area for high voltage SiC power devices. Current SiC termination designs derived from Si technology face new design issues when confronted with the unique physical properties and processing constraints of SiC. This paper presents the design and comparison of the prevailing planar and non-planar edge termination techniques, including: field plates, junction termination extensions (JTE), floating guard rings, and junction beveling. Termination structures are examined with respect to device type, influence of oxide charge, and current processing limitations.