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We report a study on the surface-leakage current in GaN/InGaN double heterojunction bipolar transistors (DHBTs) that are grown on a sapphire substrate. Surface-leakage-current densities on an unpassivated DHBT are 9.6 times 10-5 - 5.8 times 10-4 A/cm for JC = 0.5-50 A/cm2. A fabricated n-p-n GaN/InGaN DHBT shows the common-emitter dc current gain of 42, the collector-current density of 5.2 kA/cm2, and the common-emitter breakdown voltage (BVCEO) of 75 V.

BackgroundHaemolytic-uremic syndrome (HUS) is a severe, life-threatening disease with symptoms such as haemolytic anaemia, renal failure, and a low platelet count. Possible aetiology includes bacterial infections, medication, post-hematopoietic cell transplantation, pregnancy, autoimmune disease, and acquired immunodeficiency syndrome.Case presentationWe report the case of a 21-year-old healthy man who developed acute renal failure caused by HUS. Typical symptoms of HUS combined with severe uraemia developed following a large local reaction after suspectedSolenopsis invicta(fire ant) bites. He was successfully treated with plasma exchange and achieved complete recovery of renal function.ConclusionThis is the first case illustrating a serious systemic reaction of HUS to fire ant bites, and highlights this severe complication in patients who sustain fire ant bites.

We report high performance GaN-based npn heterojunction bipolar transistors (HBTs) grown by metalorganic chemical vapor deposition (MOCVD) with state-of-the-art high collector current density (JC) and low knee voltage (Vknee). For HBTs grown on sapphire, the common-emitter I-V characteristics show high JC > 16 kA/cm2 with an offset voltage (Voffset) of

We report an electroluminescence (EL) study on npn GaN/InGaN heterojunction bipolar transistors (HBTs). Three radiative recombination paths are resolved in the HBTs, corresponding to the band-to-band transition (3.3 eV), conduction-band-to-acceptor-level transition (3.15 eV), and yellow luminescence (YL) with the emission peak at 2.2 eV. We further study possible light emission paths by operating the HBTs under different biasing conditions. The band-to-band and the conduction-band-to-acceptor-level transitions mostly arise from the intrinsic base region, while a defect-related YL band could likely originate from the quasi-neutral base region of a GaN/InGaN HBT. The IB-dependent EL intensities for these three recombination paths are discussed. The results also show the radiative emission under the forward-active transistor mode operation is more effective than that using a diode-based emitter due to the enhanced excess electron concentration in the base region as increasing the collector current increases.

Peritoneal dialysis (PD) is one type of renal replacement therapy, but potential peritoneal damage and gastrointestinal (GI) tract adverse effects during long-term exposure to bio-incompatible dialysate remain a concern. Although GI disease frequently occurs in dialysis patients, whether the risk of GI diseases differs among PD and hemodialysis (HD) or non-uremic groups is still uncertain. In this retrospective cohort study, data were obtained from the National Health Insurance Research Database, which includes almost all dialysis patients in Taiwan. Between 2000 and 2009, a total of 1791 PD and 8955 HD incident patients were enrolled and matched for age and sex or for propensity score. In addition, a comparison cohort of 8955 non-uremic patients was also selected. Individuals were monitored for the occurrence of common GI diseases until 2010, and data were analyzed using several different models. Generally speaking, the results showed that the risk of gastroesophageal reflux, intestinal obstruction or adhesions, and abdominal hernia was significantly higher in the PD group, whereas the risk of peptic ulcer disease and lower GI diverticula and bleeding was significantly greater in the HD group. Meanwhile, the risk of mesenteric ischemia, liver cirrhosis, and acute pancreatitis was higher in dialysis patients, but was not significantly different between the PD and HD groups; moreover, the risk of appendicitis in the PD group appeared to be lower than that in the HD group. In conclusion, dialysis patients have a higher risk of most common GI diseases, and PD and HD modalities are associated with different GI diseases.

We report a comparative study of the device performance of III-nitride (III-N) heterojunction field-effect transistors (HFETs) and metal-insulator-semiconductor field-effect transistors (MISFETs). The influence of a remote-oxygen-plasma treatment was investigated. The plasma-treated recessed-gate HFETs and MISFETs show normally-off characteristics with higher peak transconductance, lower sub-threshold slope, smaller hysteresis. An on-off ratio greater than 2.2E11 with a significant suppression of gate leakage can be achieved in plasma-treated III-N MISFETs. A drain current transient measurement was performed to analyze the traps in these devices and possible origins of these traps are studied. Six traps with characteristic time constants (τ) ranging from 180 s to 3 ms are identified in both HFETs and MISFETs, in addition to a trap which is associated with the ALD-grown gate dielectrics for the MISFETs. The results suggest that improved device performance in these plasma-treated III-N FETs is attributed to the reduced trap states with τ 2 s) cannot be reduced by the plasma treatment and are related to the oxygen and carbon impurities and the buffer traps in the bulk semiconductors.

We report on III–nitride (III–N) avalanche phototransistor (APT) action by illuminating ultraviolet (UV) photons onto a GaN/InGaN npn heterojunction bipolar transistor in an open-base configuration. A high responsivity of >1 A/W was measured for the device operating at a collector-to-emitter voltage (VCE) of 68 A/W at VCE = 95 V. The InGaN APT demonstrates the feasibility of using III–N bipolar transistor structures for high-sensitivity UV photodetection applications.

Background Peritoneal dialysis (PD) therapy is known to induce morphological and functional changes in the peritoneal membrane. Long-term exposure to conventional bio-incompatible dialysate and peritonitis is the main etiology of inflammation. Consequently, the peritoneal membrane undergoes structural changes, including angiogenesis, fibrosis, and hyalinizing vasculopathy, which ultimately results in technique failure. The epithelial-to-mesenchymal transition (EMT) of mesothelial cells (MCs) plays an important role during the above process; however, the clinical parameters associated with the EMT process of MCs remain to be explored. Methods To investigate the parameters impacting EMT during PD therapy, 53 clinical stable PD patients were enrolled. EMT assessments were conducted through human peritoneal MCs cultured from dialysate effluent with one consistent standard criterion (MC morphology and the expression of an epithelial marker, cytokeratin 18). The factors potentially associated with EMT were analyzed using logistic regression analysis. Primary MCs derived from the omentum were isolated for the in vitro study. Results Forty-seven percent of the patients presented with EMT, 28% with non-EMT, and 15% with a mixed presentation. Logistic regression analysis showed that patients who received persistent PD therapy (dwelling time of 24 h/day) had significantly higher EMT tendency. These results were consistent in vitro. Conclusions Dwelling time had a significant effect on the occurrence of EMT on MCs.

III-nitride (III-N) heterojunction bipolar transistors (HBTs) are a less-explored electronic device technology due to the myriad research issues in material growth, device design and fabrication associated with these devices. For III-N HBTs, npn-GaN/InGaN heterostructures provide the benefits of mitigating the poor base electrical conductivity of p-type GaN and the problematic magnesium incorporation issues. Consequently, InGaN-base III-N HBTs are promising for next-generation high-power RF III-N systems. This paper will describe the current development status of npn GaN/InGaN HBTs grown either on sapphire or free-standing (FS) GaN substrates using optimized metalorganic chemical vapor deposition (MOCVD) and refined HBT processing techniques. Recombination current paths in GaN/InGaN HBTs are studied and small-signal equivalent circuits are developed. The extracted device model indicates that, with further device fabrication technique development, Johnson's figure of merit (JFOM) of GaN/InGaN HBTs can be as high as 5 THz V.

Data and analysis are presented for NpN-GaN/InGaN/GaN double-heterojunction bipolar transistors (HBTs) grown and fabricated on a free-standing GaN (FS-GaN) substrate in comparison to that on a sapphire substrate to investigate the effect of dislocations in III-nitride HBT epitaxial structures. The performance characteristics of HBTs on FS-GaN exhibit a maximum collector current density of ∼12.3 kA/cm2, dc current gain of ∼90, and maximum differential gain of ∼120 without surface passivation, representing a substantial improvement over similar devices grown on sapphire. This is attributed to the reduction in threading dislocation density afforded by using a homoepitaxial growth on a high-crystalline-quality substrate. The minority carrier diffusion length increases significantly owing to not only a mitigated carrier trap effect via fewer dislocations, but also possibly reduced microscopic localized states.

We describe a method to change the threshold voltage of heterostructure field-effect transistors (HFETs) using InxAl1−xN/GaN heterostructures by using polarization and strain modification in the InAlN barrier layer to realize enhancement-mode operation. The threshold voltage and electronic band structure of the heterostructures were calculated for different indium compositions in the InAlN layer. Band structure calculations predict the enhancement-mode operation of compressively strained InAlN/GaN HFETs with an indium composition higher than 0.25. Studies of InAlN/GaN HFETs with different In alloy compositions show that the sheet resistance increases and the carrier concentration decreases for the heterostructures with increasing indium composition due to changes in the compressive strain and polarization in the InAlN barrier layer. Fabricated HFETs show threshold voltages of −2.5, −0.75, and +0.2 V for In∼0.18Al∼0.82N/GaN, In∼0.22Al∼0.78N/GaN, and In∼0.25Al∼0.75N/GaN HFETs, respectively, corresponding to...

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