Low temperature mobility in hafnium-oxide gated germanium p-channel metal-oxide-semiconductor field-effect transistors

Effective mobility measurements have been made at 4.2 K on high performance high-k gated germanium p-type metal-oxide-semiconductor field effect transistors with a range of Ge/gate dielectric interface state densities. The mobility is successfully modelled by assuming surface roughness and interface charge scattering at the SiO2 interlayer/Ge interface. The deduced interface charge density is approximately equal to the values obtained from the threshold voltage and subthreshold slope measurements on each device. A hydrogen anneal reduces both the interface state density and the surface root mean square roughness by 20%

Heterogeneous Integration and Fabrication of III-V MOS Devices in a 200mm Processing Environment

We report on the fabrication of MOS capacitors on 200 mm virtual GaAs substrates using a Si CMOS processing environment. The fabricated capacitors were comparable to those processed on bulk GaAs material. Topside contact was made to the GaAs using a novel CMOS compatible self-aligned NiGe contact scheme resulting in a measured contact resistance of 0.26 [ohm sign].cm. Cross-contamination from various III-V substrates was investigated and it was found that by limiting the thermal budget to <= 300C cross-contamination from the outgassing of In, Ga and As could be eliminated. For wet processing the judicious choice of recipe and processing conditions resulted in no significant cross-contamination being detected as determined by TXRF monitoring. This achievement enables III-V device production using state-of-the-art Si processing equipment.Peer reviewe

European registry of type A aortic dissection (ERTAAD) - rationale, design and definition criteria

Correction: Volume16 Issue1 Article Number225 DOI10.1186/s13019-021-01606-8Background: Acute Stanford type A aortic dissection (TAAD) is a life-threatening condition. Surgery is usually performed as a salvage procedure and is associated with significant postoperative early mortality and morbidity. Understanding the patient's conditions and treatment strategies which are associated with these adverse events is essential for an appropriate management of acute TAAD. Methods: Nineteen centers of cardiac surgery from seven European countries have collaborated to create a multicentre observational registry (ERTAAD), which will enroll consecutive patients who underwent surgery for acute TAAD from January 2005 to March 2021. Analysis of the impact of patient's comorbidities, conditions at referral, surgical strategies and perioperative treatment on the early and late adverse events will be performed. The investigators have developed a classification of the urgency of the procedure based on the severity of preoperative hemodynamic conditions and malperfusion secondary to acute TAAD. The primary clinical outcomes will be in-hospital mortality, late mortality and reoperations on the aorta. Secondary outcomes will be stroke, acute kidney injury, surgical site infection, reoperation for bleeding, blood transfusion and length of stay in the intensive care unit. Discussion: The analysis of this multicentre registry will allow conclusive results on the prognostic importance of critical preoperative conditions and the value of different treatment strategies to reduce the risk of early adverse events after surgery for acute TAAD. This registry is expected to provide insights into the long-term durability of different strategies of surgical repair for TAAD.Peer reviewe

SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues

Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

First-principles study of the structural and electronic properties of (100)Ge/Ge(M)O-2 interfaces (M=Al, La, or Hf)

The structural and electronic properties of (100)Ge/Ge(M)O-2 interfaces, with M=Al, La, or Hf, are investigated using density functional theory. When a Ge atom is substituted by a Hf atom in the GeOx (suboxide) interfacial layer, a Ge-Hf bond is formed due to the fivefold coordination of Hf in the GeOx matrix. The formation of this bond gives rise to a defect level in the upper part of the Ge energy band gap. On the other hand, the incorporation of Al or La in the interfacial layer results only in the formation of Al-O-Ge or La-O-Ge bonds at/near the interface due to the fourfold coordination of these metals in the GeOx matrix. This gives rise to a surface-state free Ge energy band gap. These findings highlight the advantage of lower coordinated metal oxides that tend to form germanate layers in contact with Ge for their potential use as gate stacks in high performance metal-oxide-semiconductor field effect transistors. (C) 2008 American Institute of Physics.status: publishe

Selective epitaxial growth of InP in STI trenches on off-axis Si(001) substrates

peer reviewedWe report high quality InP layers selectively grown in shallow trench isolation structures on 6 degree offcut Si (001) substrates capped with a thin Ge buffer layer. The Ge layer was used to reduce the thermal budget for surface clean and double step formation. The atomic steps on the Ge surface were recovered after a bake at 680°C. Smooth nucleation layer was obtained at 420°C on the Ge surface. Baking the Ge surface in As ambient facilitates the InP nulceation and improves the InP crystalline quality. This improvement is attributed to the effective As adsorption on the Ge surface and the polar Ge:As surface prevents the islanding of InP seed layer. Stacking faults were found in the InP layers as a result of threading dislocation dissociation and high quality InP layers were obtained in trenches with aspect ratio greater than 2

Electrical study of sulfur passivated In₀.₅₃Ga₀.₄₇As MOS capacitor and transistor with ALD Al₂O₃ as gate insulator

In this paper we compare the interface trap distributions Dit(E) of sulfur treated Al₂O₃/In₀.₅₃Ga₀.₄₇As interfaces, which underwent MOS capacitor and transistor fabrication processes. Lower interface trap densities were found close to the conduction band edge for both cases. The inversion channel MOSFET achieves high device performance despite the fact that its oxide-semiconductor interface quality is a notch below that of the MOS capacitor with optimized process.status: publishe

On the interface state density at In₀.₅₃Ga₀.₄₇As/oxide interfaces

The authors model the capacitance-voltage (CV) behavior of In0.53Ga0.47As metal-oxide-semiconductor (MOS) structures and compare the results to experimental CV-curves. Due to the very low conduction band density of states, ideal III-V MOS structures should present an asymmetric CV behavior, with lower accumulation capacitance on the conduction band side. The absence of this asymmetric CV shape in experimental CV curves points toward the presence of additional states inside the conduction band at the oxide-semiconductor interface. Comparisons between the model and experimental data allow the determination and approximate quantification of a large acceptorlike interface state density above the conduction band edge energy.status: publishe