Search

There is a growing interest in the exploration of the nitride material family for radically scaled, high frequency, ultrasonic devices by epitaxial growth techniques. Furthermore, the introduction of epitaxial growth techniques to conventional nitride‐based acoustic technology opens the door to exciting new families of structures for phonon confinement. As the need for higher frequency communications increases, both piezoelectrics and electrodes must scale to smaller dimensions. It has recently become possible to epitaxially grow single‐crystalline, wurtzite AlN/NbN piezoelectric/metal heterostructures. The epitaxial NbN films maintain high crystalline quality and electrical conductivity down to several nanometers thickness. This study demonstrates preliminary results on the feasibility of an all‐epitaxial bulk acoustic wave technology by growing and characterizing the radio frequency (RF) properties of an epitaxial AlN/NbN heterostructure. [ABSTRACT FROM AUTHOR]

Nijmegen breakage syndrome caused by biallelic pathogenic variants of the DNA‐damage response gene NBN, is characterized by severe microcephaly, cancer proneness, infertility, and karyotype abnormalities. We previously reported NBN variants in siblings suffering from fertility defects. Here, we identify a new founder NBN variant (c.442A>G, p.(Thr148Ala)) in Lebanese patients associated with isolated infertility. Functional analyses explored preserved or altered functions correlated with their remarkably mild phenotype. Transcript and protein analyses supported the use of an alternative transcript with in‐frame skipping of exons 4–5, leading to p84‐NBN protein with a preserved forkhead‐associated (FHA) domain. The level of NBN was dramatically reduced and the MRN complex delocalized to the cytoplasm. Interestingly, ataxia–elangiectasia mutated (ATM) also shifted from the nucleus to the cytoplasm, suggesting some interaction between ATM and the MRN complex at a steady state. The ATM pathway activation, attenuated in typical patients with NBS, appeared normal under camptothecin treatment in these new NBN‐related infertile patients. Cell cycle checkpoint defect was present in these atypical patients, although to a lesser extent than in typical patients with NBS. In conclusion, we report three new NBN‐related infertile patients and we suggest that preserved FHA domain could be responsible for the mild phenotype and intermediate DNA‐damage response defects. [ABSTRACT FROM AUTHOR]

Finding a wear resistant coating for cemented carbide cutting tools in the machining of difficult to cut Ti alloys is a challenge due to their high strength and chemical reactivity. Tool manufacturers recommend physical vapor deposited (PVD) Ti x Al 1-x N (x = 0.4–0.7), and an extra NbN overlayer has shown promising potential. This study explores wear mechanisms of PVD Ti 0.45 Al 0.55 N with and without NbN overlayer and its WC-Co substrate in machining Ti alloys. To achieve an accurate understanding of tool-chip-workpiece interaction and related wear mechanisms, several approaches were employed. Tests with controlled variation of cutting speeds were complemented by process freezing experiments using the quick stop method and imitational experiments of diffusion couples. Advanced microscopy techniques were employed for accurate detection of wear products and phenomena across length scale. Findings reveal that any new design of coatings for Ti machining must combine both high mechanical integrity and resistance to diffusional dissolution and oxidation. Observed diffusional loss of Al and N from the coating results in a TiN layer which is mechanically weaker than the original coating, while the NbN overlayer reduces the Al diffusion rate, but NbN is subjected to diffusional dissolution itself. On dissolution, Nb stabilizes β-Ti and thus facilitating loss of Al, but the observed formation of intermetallic Nb 3 Al at the NbN–Ti interface works as a diffusion barrier. However, brittle Nb 3 Al can be more easily removed during machining. It was found that the coating retains longest on the edge line and protects the tool edge from failure because substrate cemented carbide wears at a faster rate than the coating with outward diffusion of C from WC grains and Co binder. [Display omitted] • Degradation of Ti 0.45 Al 0.55 N ± NbN WC-6%Co is governed by mechanical and diffusion wear. • Diffusion of Al from Ti 0.45 Al 0.55 N govern its wear forming a weaker TiN layer. • Diffusion of NbN overlayer causes its wear and forms diffusion barrier Nb 3 Al. • A novel combination of methods to explore tool wear mechanisms is introduced. • New coating designs need improved diffusional resistance for higher performance. [ABSTRACT FROM AUTHOR]

While several past studies have measured the impact of standards on indicators such as output and productivity for a variety of countries, a quantitative analysis that focuses on Belgium has not been performed yet. Based on a dataset containing sector level data spanning 25 years (1994-2018), the authors find that, next to capital investment and the number of patents, standards make a statistically significant, positive and substantial contribution to Belgian GDP as well as to labor productivity. More specifically, one additional standard will on average increase GDP by €2.04 million per year and will increase labor productivity per person employed by €11.5. In addition, standards contribute to about 0.2% of GDP, 19% of GDP growth, and 19% of labor productivity growth. [ABSTRACT FROM AUTHOR]

To optimize genetic testing, it is necessary to establish the spectrum of breast cancer‐predisposing mutations in particular ethnic groups. We studied 1,018 women with a strong family history for breast cancer (families with hereditary breast cancer; HBC) from genetically homogenous population of Poland, which is populated by ethnic Slavs, for mutations in 14 cancer susceptibility genes. Additionally, we compared the frequency of candidate pathogenic variants in breast cancer cases and controls. Germline mutations were detected in 512 of 1,018 probands with breast cancer (50.3%), including BRCA1/2 mutations detected in 420 families and non‐BRCA mutations seen in 92 families. Thirteen BRCA1/2 founder mutations represented 84% of all BRCA1/2‐positive cases. Seven founder mutations of CHEK2, PALB2, NBN and RECQL represented 73% of all non‐BRCA‐positive cases. Odds ratios for hereditary breast cancer were 87.6 for BRCA1, 15.4 for PALB2, 7.2 for CHEK2, 2.8 for NBN and 15.8 for RECQL. Odds ratios for XRCC2, BLM and BARD1 were below 1.3. In summary, we found that 20 founder mutations in six genes (BRCA1/2, CHEK2, PALB2, NBN and RECQL) are responsible for 82% of Polish hereditary breast cancer families. A simple test for these 20 mutations will facilitate genetic testing for breast cancer susceptibility in Poland. It may also facilitate genetic testing for breast cancer susceptibility in other Slavic populations and women of Slavic descent worldwide. What's new? Poland is a genetically homogeneous population similar to Iceland, currently designing national policies for genetic testing. To define the range of pathogenic mutations, the authors conducted a large analysis of breast cancer susceptibility genes, defining pathogenic mutations in 50.3% families with hereditary breast cancer. They identified 20 distinct founder mutations in six genes that were responsible for more than 80% of all detected mutations; these 20 mutations could be combined in a single genetic test of breast cancer susceptibility in Polish women. [ABSTRACT FROM AUTHOR]

Background: NBN 657del5 founder mutation predisposes to breast and prostate cancer. Recently, it has been reported that the pathogenicity of this mutation with regard to prostate cancer risk is modified by a missense variant of the same gene (E185Q). Methods: To evaluate the interaction of the 657del5 and E185Q founder alleles of NBN on breast cancer risk in Poland, 4964 women with breast cancer and 6152 controls were genotyped for these two recurrent variants of NBN (657del5 truncating variant and E185Q missense variant). Results: The NBN 657del5 mutation was detected in 57 of 4964 unselected cases and in 35 of 6152 controls (OR = 2.0, p = 0.001). The E185Q GG genotype was detected in 2167 of 4964 unselected cases and in 2617 of 6152 controls (OR = 1.04, p = 0.3). In carriers of the 657del5 deletion, the elevated cancer risk was restricted to women with the GG genotype of the E185Q variant (OR = 3.6, 95% CI 1.9–6.6; p < 0.0001). Among women with other E185Q genotypes, the OR associated with 657del5 was 1.0 (95% CI 0.5–1.8; p = 0.9). The interaction between the two alleles was statistically significant (homogeneity p = 0.003). Conclusion: In Poland, the pathogenicity of the NBN 657del5 mutation is restricted to women with a homozygous GG genotype of missense variant of the same gene (E185Q). This is the first clear example whereby a moderate penetrance breast cancer gene is impacted by a genetic modifier. [ABSTRACT FROM AUTHOR]

Mid-wavelength infrared detectors have been fabricated in the nBn configuration using the InAs/InAsSb superlattice as the absorber. Possible impediments in the valence band can interfere with the transport of holes that represent the signal. We demonstrate that the thermal activation energy of the photocurrent density, as a function of the applied bias voltage, can be a very sensitive probe of the valence band features. We identify and measure two types of impediments, the hole-block due to a band misalignment and the localization sites formed by fluctuations in the superlattice layer thicknesses. The latter are found to dominate the temperature dependence of the hole mobility. Our inferred localization characteristics are consistent with published results obtained by other techniques. [ABSTRACT FROM AUTHOR]

We recently reported mid-wavelength infrared (MWIR) InAs/InAsSb type II strained-layer superlattice (T2SLS) unipolar barrier detectors and focal-plane arrays with significantly higher operating temperature than InSb. Herein, we document the development leading to the MWIR InAs/InAsSb T2SLS detectors at the NASA Jet Propulsion Laboratory. We also briefly compare the InAs/InAsSb T2SLS with some other approaches. [ABSTRACT FROM AUTHOR]

Introduction While the current nomenclature of psychotropic drugs is disease-based, their approved indications do not always match their classifications. Methods Information on approved indications of "second-generation antipsychotics" and "newer antidepressants" that are available in the United States (US), the United Kingdom (UK), France, Germany, and Japan were extracted from their packet inserts. Results A significant proportion of "atypical antipsychotics" were approved for psychiatric conditions other than psychotic disorders (i. e., bipolar disorder, major depressive disorder, and autistic disorder) as follows: 76.9% in the US, 66.7% in the UK, 66.7% in France, 60.0% in Germany, and 44.4% in Japan. Likewise, more than half of "newer antidepressants" had approved indications for psychiatric conditions other than depression (e. g., panic disorder, obsessive compulsive disorder, social anxiety disorder, general anxiety disorder, and post-traumatic stress disorder): 56.3% in the US, 69.2% in the UK, 69.2% in France, 50.0% in Germany, and 62.5% in Japan. Conclusions Our results raise concerns regarding generic terminologies of "antipsychotics" and "antidepressants" since the conventional indication-based nomenclature does not fit well with the official indication. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study was to establish the contribution of four founder alleles of NBN to prostate cancer risk and cancer survival. Materials and Methods Five thousand one hundred eighty-nine men with prostate cancer and 6,152 controls were genotyped for four recurrent variants of NBN (657del5, R215W, I171V, and E185Q). Results The NBN 657del5 mutation was detected in 74 of 5,189 unselected cases and in 35 of 6,152 controls (odds ratio [OR], 2.5; p < 0.001). In carriers of 657del5 deletion, the cancer risk was restricted to men with the GG genotype of the E185Q variant of the same gene. Among men with the GG genotype, the OR associated with 657del5 was 4.4 (95% confidence interval [CI], 2.4 to 8.0). Among men with other E185Q genotypes, the OR associated with 657del5 was 1.4 (95% CI, 0.8 to 2.4) and the interaction was significant (homogeneity p=0.006). After a median follow-up of 109 months, mortality was worse for 657del5 mutation carriers than for non-carriers (hazard ratio [HR], 1.6; p=0.001). The adverse effect of 657del5 on survival was only seen on the background of the GG genotype of E185Q (HR, 1.9; p=0.0004). Conclusion The NBN 657del5 mutation predisposes to poor prognosis prostate cancer. The pathogenicity of this mutation, with regards to both prostate cancer risk and survival, is modified by a missense variant of the same gene (E185Q). [ABSTRACT FROM AUTHOR]

• Carrier localization in the InAsSb/InSb digital alloy nBn detector varies substantially with spatial location. • This is likely caused by macro-scale nonuniformities in the growth at the mm scale. • These nonuniformities may include sub-monolayer fluctuations in layer thickness and fluctuations in alloy composition. Recently we have demonstrated a novel method of extending the cut-off wavelength of InAsSb nBn detectors, by incorporating a series of monolayers of InSb, which we have termed a digital alloy. In recent work we have shown that while increasing temperature from 15 K to 40 K we observe a 14 meV blue shift of the photoluminescence peak energy and a decrease in minority carrier lifetime. We have hypothesized this effect is due to carrier localization caused by macro-scale fluctuations in layer thickness or alloy composition. Here we study the spatial variation of this effect over the surface of a sample, demonstrating significant variation with position. We discuss implications of this for the carrier localization hypothesis. [ABSTRACT FROM AUTHOR]

Abstract The practical application of Lithium Sulfur battery is limited due to its rapid capacity fading and early battery failure caused by the shuttling of soluble polysulfide. Thus, the key to improve the performance of a Lithium Sulfur battery is to suppress the shuttling effect. Herein, we report a NbN modified PP separator with high performance for Lithium Sulfur battery applications. The NbN functionalized layer of the separator can strongly interact with soluble polysulfide species, as demonstrated by both experimental investigation and theoretical verification. As a result of the high polysulfide affinity, the composite separator effectively prevents the shuttling of soluble polysulfide through the separator. Besides, the high electrolyte wettability of NbN modification layer lowers the resistance of Li+ transport through the separator. Due to these favorable features, Lithium Sulfur battery assembled with the multifunctional NbN modified separator exhibits excellent cycling performance with a reversible capacity of 554.6 mAh g−1 after 200 cycles at 0.2C. The significantly improved rate performance of the battery based on the modified separator is also demonstrated. Our results show that NbN is a promising material for the modification of separators in Lithium Sulfur battery and the strategy of separator engineering is effective for improving the performance of Lithium Sulfur battery. Graphical abstract Image 1 Highlights • A NbN modified separator is introduced for Li S battery. • The NBN functionalization improves the Li+ transport through the separator. • The NBN coating effectively prevents the shuttling of soluble LiPS. [ABSTRACT FROM AUTHOR]

Background: Solid tumours are less oxygenated than normal tissues. This is called tumour hypoxia and leads to resistance to radiotherapy and chemotherapy. The molecular mechanisms underlying such resistance have been investigated in a range of tumour types, including the adult brain tumours glioblastoma, yet little is known for paediatric brain tumours. Medulloblastoma (MB) is the most common malignant brain tumour in children. We aimed to elucidate the impact of hypoxia on the sensitivity of MB cells to chemo- and radiotherapy.Methods: We used two MB cell line (D283-MED and MEB-Med8A) and a widely used glioblastoma cell line (U87MG) for comparison. We applied a range of molecular and cellular techniques to measure cell survival, cell cycle progression, protein expression and DNA damage combined with a transcriptomic micro-array approach in D283-MED cells, for global gene expression analysis in acute and chronic hypoxic conditions.Results: In D283-MED and U87MG, chronic hypoxia (5 days), but not acute hypoxia (24 h) induced resistance to chemotherapy and X-ray irradiation. This acquired resistance upon chronic hypoxia was present but less pronounced in MEB-Med8A cells. Using transcriptomic analysis in D283-MED cells, we found a large transcriptional remodelling upon long term hypoxia, in particular the expression of a number of genes involved in detection and repair of double strand breaks (DSB) was altered. The levels of Nibrin (NBN) and MRE11, members of the MRN complex (MRE11/Rad50/NBN) responsible for DSB recognition, were significantly down-regulated. This was associated with a reduction of Ataxia Telangiectasia Mutated (ATM) activation by etoposide, indicating a profound dampening of the DNA damage signalling in hypoxic conditions. As a consequence, p53 activation by etoposide was reduced, and cell survival enhanced. Whilst U87MG shared the same dampened p53 activity, upon chemotherapeutic drug treatment in chronic hypoxic conditions, these cells used a different mechanism, independent of the DNA damage pathway.Conclusion: Together our results demonstrate a new mechanism explaining hypoxia-induced resistance involving the alteration of the response to DSB in D283-MED cells, but also highlight the cell type to cell type diversity and the necessity to take into account the differing tumour genetic make-up when considering re-sensitisation therapeutic protocols. [ABSTRACT FROM AUTHOR]

Highlights • Delta-doped layers have been utilized to get HgCdTe nBn configurations. • Short (SWIR), medium (MWIR) and long (LWIR) wave infrared bands are examined. • Strong suppression of dark current have been demonstrated. • No degradation in photo response has been observed. • This methodology is especially useful when the carrier lifetime is limited. Abstract Delta-doped layers together with compositionally grading have been utilized to get nBn configurations for the HgCdTe material system in all the short-wave (SWIR), medium-wave (MWIR) and long-wave (LWIR) infrared bands. Shockley Read Hall (SRH), trap-assisted tunneling (TAT), Auger and radiative recombination mechanisms have been included in the analyses and strong suppression of SRH and TAT currents have been demonstrated with the designed structures. This methodology is especially useful when the carrier lifetime is limited due to alternative substrate usage. No degradation in photo-response has been observed as adjusting the valence band offset is quite flexible with the delta-doped nano-layers and the valence band barrier can be completely removed. Calculations have been performed for 1–3 μs lifetime targeting the alternative substrate applications and up to 60 degrees of increase in the operation has been shown to be possible. [ABSTRACT FROM AUTHOR]

Highlights • Theoretical analysis provides simple comparisons of bulk and type-II superlattice infrared absorbers. • Covering short-wavelength infrared to very long wavelength infrared. • Type-II superlattice mid-wavelength infrared detector and focal plane array out-performs InSb. Abstract Advances in bulk III-V semiconductor material such as InGaAsSb and metamorphic InAsSb, as well as in a variety of type-II superlattices such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short to the very long wavelength infrared. We perform basic theoretical analysis to provide comparisons of different infrared materials. We also briefly report experimental results on a mid-wavelength InAs/InAsSb type-II superlattice unipolar barrier infrared detector and a focal plane array with significantly higher operating temperature than InSb. [ABSTRACT FROM AUTHOR]

Highlights • Dark-current degradation in nBn detectors under proton irradiation re-investigated. • Previously published work neglected irradiation-induced doping density increase. • New results describe varying power-law between nBn dark-current and proton fluence. Abstract Recent investigations demonstrated that III-V-based nBn infrared detectors typically experience relatively significant performance degradation under 63 MeV proton irradiation due to displacement damage, limiting their viability for certain space-based applications. Additionally, the investigations suggested, based on simplified expressions, that the nBn's diffusion-limited dark-current would transition from a linear-dependence on proton fluence to a square-root-dependence as the minority carrier recombination lifetime decreased and the subsequently decreasing diffusion length became less than the thickness of the detector's quasi-neutral absorbing region. Here, a closer examination of this expected behavior is reported on. Evidence from multiple nBn detector rad-tolerance experiments and simple numerical simulations indicated the behavior of the nBn's diffusion-current under proton irradiation can be more complicated than was previously suggested. For example, in some nBn detectors proton irradiation was observed to increase the doping density of the absorber sufficient to impact the diffusion-current and lessen its power-law-dependence on the proton fluence. This increase was confirmed by analysis of in situ capacitance–voltage measurements on an irradiated nBn detector, which found an n-type carrier addition rate ∼ 140 cm−1. Simulations showed this level of carrier addition can lead to a ∼ 75 % reduction in the expected diffusion-current density for an equivalent dose of 100 krad(Si). Simulations also showed the nBn diffusion-current's instantaneous power law-dependence on proton fluence peaked well below unity and then began approaching −.5 rather than.5, which was suggested by those previous investigation. A high native defect density prior to irradiation and finite surface recombination velocity were both found to reduce the initial power-law dependence and shift its peak position. [ABSTRACT FROM AUTHOR]

Introduction : The NBN gene product is part of the MRE11/RAD50/ NBN complex, which plays an essential role in genomic stability. In the study we try to answer the question what is the effect of irradiation on DNA synthesis, NBN gene expression and chromosomal stability in cells with homozygous c.657-661del, and heterozygous c.657-661del, p.I171V and p.R215W NBN gene mutations. Material and methods : Immortalized B-lymphocytes with NBN gene mutations were X-ray irradiated at doses of 1, 2, 5 and 8 Gy/min. Radioresistant DNA synthesis rate and the percentage of cells in phase S was analyzed by 3H thymidine and BrdU incorporation assays. NBN gene expression was quantified by real-time PCR with TaqMan fluorescent probe. Results : Increasing the irradiation dose resulted in gradual decrease of 3H thymidine incorporation in all cells, but significantly only in homo- and heterozygous c.657-661del cells (p-values < 0.0001). After irradiation the relative expression of NBN was significantly higher in homozygous c.657-661del and heterozygous p.R215W cells as compared to heterozygous c.657-661del, p.I171V and control cells (p < 0.01). All cells with NBN gene mutations showed significantly higher total number of chromosomal aberrations per metaphase as compared to control cells, with the highest number of aberrations in homozygous c.657-661del cells (p < 0.001). Conclusions : The results obtained indicate that homozygous c.657-661del mutation affects cell sensitivity to irradiation. Moreover, homozygous variant is associated with disturbance in the activation of cell cycle checkpoints and with defects in DNA repair. In turn, heterozygous c.657-661del, p.R215W and p.I171V mutations do not substantially alter the radiosensitivity.

Clinical importance of the most common CHEK2 (IVS2+1 G>A, 1100delС, I157T and del5395) and NBN (R215W and 657del5) gene mutations for breast cancer development in Macedonian breast cancer patients is unknown. We performed a case-control study including 300 Macedonian breast cancer patients and 283 Macedonian healthy controls. Genotyping was done using a fast and highly accurate single-nucleotide primer extension method for the detection of five mutations in a single reaction. The detection of the del5395 was performed using an allele-specific duplex polymerase chain reaction (PCR) assay. We have found that mutations were more frequent in breast cancer patients (n = 13, 4.3%) than in controls (n = 5, 1.8%), although without statistical significance. Twelve patients were heterozygous for one of the analyzed mutations, while one patient had two mutations (NBN R215W and CHEK2 I157T). The most frequent variant was I157T, found in 10 patients and four controls (p = 0.176) and was found to be associated with familial breast cancer (p = 0.041). CHEK2 1100delC and NBN 657del5 were each found in one patient and not in the control group. CHEK2 IVS2+1G>A and del5395 were not found in our cohort. Frequencies of the studied mutations are low and they are not likely to represent alleles of clinical importance in the Macedonian population.

With a growing demand for detecting light at the single-photon level in various fields, researchers are focused on optimizing the performance of superconducting single-photon detectors (SSPDs) by using multiple approaches. However, input light coupling for visible light has remained a challenge in the development of efficient SSPDs. To overcome these limitations, we developed a novel system that integrates NbN superconducting microwire photon detectors (SMPDs) with gap-plasmon resonators to improve the photon detection efficiency to 98% while preserving all detector performance features, such as polarization insensitivity. The plasmonic SMPDs exhibit a hot-belt effect that generates a nonlinear photoresponse in the visible range operated at 9 K (∼0.64 T c ), resulting in a 233-fold increase in phonon-electron interaction factor (γ) compared to pristine SMPDs at resonance under CW illumination. These findings open up new opportunities for ultrasensitive single-photon detection in areas like quantum information processing, quantum optics, imaging, and sensing at visible wavelengths.

The absorption can be amplified by using tungsten silicide (WSi) and metallic nano-antennas, which is related with the detection efficiency of a superconducting nanowire single-photon detector based on surface plasmons. A metal slot sandwiched between two hydrogen silsequioxane (HSQ), WSi nanowire, and metallic fan nano-antennas are the elements of the proposed single-photon detector. The slot is also filled with HSQ and WSi nanowire is inserted in the top of the slot. Metallic fan nano-antennas are added no WSi nanowire and the all these elements are deposed on the sapphire substrate. Our results show that the absorption/the detection efficiency of our proposed structure is much larger than the one with the niobium nitride (NbN) nanowire. There is an optimal width of WSi nanowire and the distance between WSi nanowire and metallic nano-antennas for the absorption/the detection efficiency of the detector. Our structure provides suitable parameters for designing SNSPD in experiments. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Local electron density in a ion-gated metal (NbN) is calculated by DFT. • For doping up to 1013–1014 e/cm2, screening is confined to the first atomic layer. • Screening extends to the third atomic layer for surface density ≈ 1015 cm−2. • Electric fields are screened by accumulation layer and pristine charge polarization. Abstract The interaction between an electric field and the electric charges in a material is described by electrostatic screening, which in metallic systems is commonly thought to be confined within a distance of the order of the Thomas–Fermi length. The validity of this picture, which holds for surface charges up to ∼ 10 13 cm−2, has been recently questioned by several experimental results when dealing with larger surface charges, such as those routinely achieved via the ionic gating technique. Whether these results can be accounted for in a purely electrostatic picture is still debated. In this work, we tackle this issue by calculating the spatial dependence of the charge carrier density in thin slabs of niobium nitride via an ab initio density functional theory approach in the field-effect transistor configuration. We find that perturbations induced by surface charges ≲ 10 14 cm−2 are mainly screened within the first layer, while those induced by larger surface charges ∼ 10 15 cm−2 can penetrate over multiple atomic layers, in reasonable agreement with the available experimental data. Furthermore, we show that a significant contribution to the screening of large fields is associated not only to the accumulation layer of the induced charge carriers at the surface, but also to the polarization of the pre-existing charge density of the undoped system. [ABSTRACT FROM AUTHOR]

We report focal plane array (FPA) results on a mid-wavelength InAs/InAsSb type-II strained layer superlattice (T2SLS) unipolar barrier infrared detector with a cutoff wavelength of 5.4 μm. For 300 K background in the 3–5-μm band, f/2 aperture, an FPA operating at 150 K exhibits a mean noise equivalent differential temperature (NEDT) of 18.5 mK, and an NEDT operability of 99.7%. The NEΔT distribution has a width of 8 mK, with no noticeable distribution tail, indicating excellent uniformity. The mean noise-equivalent irradiance is 9.1 × 1011 photons/sec-cm2. The mean quantum efficiency is 49.1% without antireflection coating, and the mean specific detectivity (D*) is 2.53 × 1011 cm-Hz½/W. Benefitting from an absorber material with a much longer Shockley–Read–Hall minority carrier lifetime, and a device architecture that suppresses generation-recombination and surface-leakage dark current, the InAs/InAsSb T2SLS barrier infrared detector FPA has demonstrated a significantly higher operating temperature than the mid-wavelength infrared market-leading InSb. [ABSTRACT FROM AUTHOR]

A method is described whereby the valence band (VB) discontinuity that is present in mercury cadmium telluride (HgCdTe)-based alloy-barrier nBn detectors can be minimized. It is numerically demonstrated that compositionally graded layers can provide the required transition between the wide bandgap CdTe barrier layer and the lattice-matched HgCdTe absorber and contact layers, although a large VB discontinuity is present. In addition, the incorporation of delta-doped ($\delta $ -doped) layers in the vicinity of the barrier region can minimize the VB discontinuity, thus blocking the flow of majority carriers and allowing unimpeded flow of photogenerated minority carriers. This strategy results in diffusion-limited dark current at low reverse bias combined with efficient collection of photogenerated carriers. The nBn structure proposed in this paper can be applied to other semiconductor materials operating in various infrared wavelength bands. The method is not limited to the nBn structure and can be applied to any xBx barrier detector structure (with ${x} = \textit {n, p}$) configuration in order to minimize the energy band discontinuity in the corresponding minority carrier band. [ABSTRACT FROM AUTHOR]

Using first principles calculations and experimental methods we show that B1 structured solid solution Ti x Nb y Al z N can be grown. The mixing free energy surface indicates that the alloys should decompose. Theoretical analysis of the thermodynamic driving force towards the spinodal decomposition shows that the force can be different in alloys with equally low thermodynamic stability but different Nb content, indicating that the detailed picture of the decomposition should also be different. Electron microscopy and nanoindentation underlines different age hardening of the samples. We demonstrate that an alloy with the optimized composition, Ti 0.42 Nb 0.17 Al 0.41 N combines high thermal stability and age hardening behavior. [ABSTRACT FROM AUTHOR]

Unipolar barrier detector design is a challenge for InGaAs material system since there is a lack of proper barrier material that blocks majority carriers and allows unimpeded flow of minority carriers. As a bandgap engineering solution, Al/Sb free all InGaAs unipolar barrier detectors have been numerically designed here by compositionally graded and delta-doped layers. Comparison with convetional heterojunction detectors results that there is at least one order of magnitude improvement in dark current without compromising any photo response performance. Detailed simulation characterization studies including sensitivity analysis with respect to the design parameters verify the robustness of the proposed structure. [ABSTRACT FROM AUTHOR]

Copyright of Zeszyty Naukowe Uczelni Vistula/ Vistula University Working Papers is the property of Vistula University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • Epitaxial growth of NbN thin films using atomic layer deposition. • An in-plane compressive strain in the NbN film grown on MgO substrates. • 50% reduced resistivity owing to an enhanced carrier mobility. • Plausible mechanism in the growth of epitaxial NbN films. The epitaxial growth of NbN thin film was accomplished via atomic layer deposition (ALD) for the first time using NbCl 5 and NH 3 as the Nb precursor and nitrogen source at a deposition temperature of 450 ℃. The cubic NbN thin film was grown epitaxially on a cubic MgO crystal through the coherent lattice matching between NbN and MgO with a small lattice mismatch (∼2.8%). A high concentration of Cl impurity of 4–5% remained in NbN thin films grown on a SiO 2 substrate using ALD. However, the Cl impurity concentration decreased to ∼ 2% in the epitaxially grown NbN thin films, which facilitated the epitaxial growth of NbN thin films on the MgO substrate. The origin was attributed to a residual strain at the NbN/MgO interface, which induced a bond length change in Nb-N-Cl. The bond length change may promote Cl desorption during NbN ALD because an in-plane compressive strain in the NbN film and an in-plane tensile strain in the MgO surface were observed. Finally, the epitaxially grown NbN thin film exhibited a 50% lower resistivity than that grown with a polycrystalline phase based on the enhanced carrier mobility owing to the improved crystallinity of epitaxial NbN thin films. [ABSTRACT FROM AUTHOR]

Background. The early diagnosis of ovarian cancer (OC) is an important problem in modern gynecological oncology due to significant detection rates for late-stage tumors. Intensive screening of patients from high-risk groups that include OC predisposition gene mutation carriers is indicated.Subjects and methods. An unselected group of 202 patients with OC and two control groups of blood donors: 591 healthy females; 1197 persons (including 591 females, 606 males) were examined. Patients and healthy individuals who identified themselves as ethnic Russians and residents of the Russian Federation participated in the study. Whole peripheral blood samples were collected at the Clinical Subdivisions of the N.N. Blokhin Russian Cancer Research Center and at the Department of Transfusiology of the Acad. B.V. Petrovsky Russian Research Center of Surgery in 2012–2013. Informed consent was obtained from all the participants. DNA was extracted using a Prep-GS-Genetics reagent kit. Real-time polymerase chain reaction genotyping assay was carried out by melting-curve analysis employing an BRCA SNP genotyping kit(BRCA1 and BRCA2 gene mutations) and original oligonucleotides (CHEK2, NBN, and BLM gene mutations). Thirteen population-specific mutations, including 7 (185delAG, 4153delA, 5382insC, 3819delGTAAA, 3875delGTCT, 300T>G, and 2080delA) in the BRCA1 gene, 1 (6174delT) in the BRCA2 gene, 3 (1100delC, IVS2+1G>A, and 470T>C) in the CHEK2 gene, 1 (657delACAAA) in the NBN gene, and 1 (1642C>T) in the BLM gene, were genotyped. Polymerase chain reaction was performed using a DTprime real-time detection thermal cycler.Results and discussion. BRCA1 and BRCA2 gene mutations were detected in 46 (22.8 %) patients with OC; the prevailing mutation in the BRCA1 gene was 5382insC (58.7 %). OC was diagnosed in 32.6 % of the patients aged 51 years or older. The rate of moderate-penetrance mutations (1100delC and IVS2+1G>A in the CHEK2 gene, 657del5 in the NBN gene, and 1642C>T in the BLM gene) was 0.5–1.0 % in the group of OC patients and 0–0.3 % in the control group of healthy women. The majority of these patients (5/6) were diagnosed with OC at age less than 50 years. The CHEK2 mutation, 470T>C, was more frequently encountered in the control group (6.6 %) than in the OC patient group (5.0 %). High rate of the CHEK2 mutation, IVS2+1G>A, was first shown for OC patients in the Russian Federation, the odds ratio was 11.9 (95 % confidence interval, 9.5–14.3; p = 0.056). It was preliminarily concluded that it played an important role in the development of OC in the Russian population; our findings should be verified in further investigations. The difference in the rate of mutations, such as 1100delC, IVS2+1G>A and 470T>C in the CHEK2 gene, 657del5 in the NBN gene, 1642C>T in the BLM gene, were insignificant in the patient and control groups, which may be related to the low population rate of these genetic markers and, in case of the CHEK2 mutation, 470T>C, may be linked to its low penetrance. By taking into account the fact that numerous studies have proven the clinical significance of all examined moderate-penetrance mutations whose prevalence in the Russian population has been confirmed by the authors of this paper, the inclusion of the mutations in a diagnostic panel to detect hereditary predisposition to OC is substantiated. The associated risks are higher for the rare mutations leading to the formation of truncated nonfunctional proteins, which are 1100delC and IVS2+1G>A in the CHEK2 gene, 657del5 in the NBN gene, and 1642C>T in the BLM gene. The penetrance of the CHEK2 mutation, 470T>C, is lower, which should be kept in mind during medical genetic counselling.Conclusion. The total rate of mutations in the BRCA1, BRCA2, CHEK2, NBN, and BLM genes in patients with OC was 30.7 %, which determines the expediency of molecular genetic screening in this category of patients.

Surface leakage and lateral diffusion currents in InAs-based nBn photodetectors have been investigated. Devices fabricated using a shallow etch processing scheme that etches through the top contact and stops at the barrier exhibited large lateral diffusion current but undetectably low surface leakage. Such large lateral diffusion current significantly increased the dark current, especially in small devices, and causes pixel-to-pixel crosstalk in detector arrays. To eliminate the lateral diffusion current, two different approaches were examined. The conventional solution utilized a deep etch process, which etches through the top contact, barrier, and absorber. This deep etch processing scheme eliminated lateral diffusion, but introduced high surface current along the device mesa sidewalls, increasing the dark current. High device failure rate was also observed in deep-etched nBn structures. An alternative approach to limit lateral diffusion used an inverted nBn structure that has its absorber grown above the barrier. Like the shallow etch process on conventional nBn structures, the inverted nBn devices were fabricated with a processing scheme that only etches the top layer (the absorber, in this case) but avoids etching through the barrier. The results show that inverted nBn devices have the advantage of eliminating the lateral diffusion current without introducing elevated surface current. [ABSTRACT FROM AUTHOR]

The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at 2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications. [ABSTRACT FROM AUTHOR]

The depletion and surface leakage dark current suppression properties of unipolar barrier device architectures such as the nBn have been highly beneficial for III–V semiconductor-based infrared detectors. Using a one-dimensional drift-diffusion model, we theoretically examine the effects of contact doping, minority carrier lifetime, and absorber doping on the dark current characteristics of nBn detectors to explore some basic aspects of their operation. We found that in a properly designed nBn detector with highly doped excluding contacts the minority carriers are extracted to nonequilibrium levels under reverse bias in the same manner as the high operating temperature (HOT) detector structure. Longer absorber Shockley–Read–Hall (SRH) lifetimes result in lower diffusion and depletion dark currents. Higher absorber doping can also lead to lower diffusion and depletion dark currents, but the benefit should be weighted against the possibility of reduced diffusion length due to shortened SRH lifetime. We also briefly examined nBn structures with unintended minority carrier blocking barriers due to excessive n-doping in the unipolar electron barrier, or due to a positive valence band offset between the barrier and the absorber. Both types of hole blocking structures lead to higher turn-on bias, although barrier n-doping could help suppress depletion dark current. [ABSTRACT FROM AUTHOR]

The molecular chaperone heat shock protein 90 (Hsp90α) regulates cell proteostasis and mitigates the harmful effects of endogenous and exogenous stressors on the proteome. Indeed, the inhibition of Hsp90α ATPase activity affects the cellular response to ionizing radiation (IR). Although the interplay between Hsp90α and several DNA damage response (DDR) proteins has been reported, its role in the DDR is still unclear. Here, we show that ataxia-telangiectasia-mutated kinase (ATM) and nibrin (NBN), but not 53BP1, RAD50, and MRE11, are Hsp90α clients as the Hsp90α inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) induces ATM and NBN polyubiquitination and proteosomal degradation in normal fibroblasts and lymphoblastoid cell lines. Hsp90α-ATM and Hsp90α-NBN complexes are present in unstressed and irradiated cells, allowing the maintenance of ATM and NBN stability that is required for the MRE11/RAD50/NBN complex-dependent ATM activation and the ATM-dependent phosphorylation of both NBN and Hsp90α in response to IR-induced DNA double-strand breaks (DSBs). Hsp90α forms a complex also with ph-Ser1981-ATM following IR. Upon phosphorylation, NBN dissociates from Hsp90α and translocates at the DSBs, while phThr5/7-Hsp90α is not recruited at the damaged sites. The inhibition of Hsp90α affects nuclear localization of MRE11 and RAD50, impairs DDR signaling (e.g., BRCA1 and CHK2 phosphorylation), and slows down DSBs repair. Hsp90α inhibition does not affect DNA-dependent protein kinase (DNA-PK) activity, which possibly phosphorylates Hsp90α and H2AX after IR. Notably, Hsp90α inhibition causes H2AX phosphorylation in proliferating cells, this possibly indicating replication stress events. Overall, present data shed light on the regulatory role of Hsp90α on the DDR, controlling ATM and NBN stability and influencing the DSBs signaling and repair. [ABSTRACT FROM AUTHOR]

Noise Equivalent Difference Temperature (NEΔT) is a standard performance metric for most infrared focal plane array (FPA) systems. The frequency bandwidth and range associated with NEΔT is normally at high frequency and it does not describe the long time noise behavior or the very low frequency noise of the FPA. Very low frequency noise measurement requires data capture that takes longer time duration and sampling interval. This study investigates low frequency noise in QWIP, nBn and LWIR n-type Complementary Barrier Infrared Detector (CBIRD) FPAs. The corner frequencies are extracted from the power spectral density (PSD) as function of frequency. The peak wavelength, quantum efficiency of QWIP detector are 6.2 μm and 2%, respectively. QWIP FPA has a mean NEΔT ∼ 25 mK at an operating temperature of 65 K and an integration time of 16 ms. The mean QWIP PSD plot shows a corner frequency of <0.5 mHz. The nBn FPA with 4 μm cut off and quantum efficiency of 67 % has NEΔT ∼ 15.6 mK at an integration time ∼7.52 ms and an operating temperature of 120 K. The nBn has corner frequency of >50 mHz. Lastly the n-type CBIRD FPA with a 50% cutoff at 8.8 μm and quantum efficiency of ∼50 % has an NEΔT ∼ 18.6 mK at an integration time of 1.86 ms and operating temperature 120 K. The superlattice FPA has a corner frequency ∼10 mHz. The investigation of the tail on the NEΔT histogram reveals that its origin is not accounted for entirely by the high noise current, but also it needs the inclusion of lower responsivity for some pixels. [ABSTRACT FROM AUTHOR]

Nijmegen breakage syndrome is an autosomal recessive disorder caused by biallelic mutation in NBN gene. It is characterized by microcephaly, growth retardation, immuno-deficiency and cancer predisposition. The monoallelic carriers of NBN gene are also reported to be at increased risk of developing various types of malignancy. We have investigated an individual with lung cancer from an extended family segregating different types of hereditary cancer over several generations, including lung, breast, ovarian, colon, prostate and renal cancers. By using next generation whole exome sequencing approach, we identified a rare heterozygous frameshift mutation in NBN gene; c.93_94delTG (Ala32HisfsTer4), which is predicted to be pathogenic together with 3 other variants; 2 being in the BRCA1 gene, c.1648A > C (p.Asn550His) and c.536A > G (p.Tyr179Cys), and one in RAD50 gene, c.3539G > A (p.Arg1180Gln). Some of the variants were also found in six out of eight clinically normal relatives, but in different combinations. To our knowledge, this is the first report of NBN gene mutation in an individual with lung cancer in the Arab world. Reporting such findings may aid in variants' risk classification and clinical decision in the future. [ABSTRACT FROM AUTHOR]

Properties of NbN and TaxN thin films grown at ambient temperatures on SiO2/Si substrates by reactive-pulsed laser deposition and reactive magnetron sputtering (MS) as a function of N2 gas flow were investigated. Both techniques produced films with smooth surfaces, where the surface roughness did not depend on the N2 gas flow during growth. High crystalline quality, (111) oriented NbN films with Tc up to 11 K were produced by both techniques for N contents near 50%. The low temperature transport properties of the TaxN films depended upon both the N2 partial pressure used during growth and the film thickness. The root mean square surface roughness of TaxN films grown by MS increased as the film thickness decreased down to 10 nm. [ABSTRACT FROM PUBLISHER]

A fabrication process for NbN films with a high transition temperature (TC) of about 17 K was developed to realize NbN/AlN/NbN superconducting-tunnel-junction array particle detectors with a high operation temperature of >1 K and a high sensitivity by using atomic layer deposition (ALD). The source (precursor) of the NbN films was (tert -butylimido)bis(diethylamino)niobium [C16H39N4Nb]. NbN films were deposited on M-plane sapphire wafers. A 50-nm-thick NbN film was deposited with a substrate temperature of about 570 K and exhibited a (TC) of 12.35 K. To improve the superconducting properties of the NbN formed by ALD, a postdeposition rapid thermal annealing process was performed. The dependence of (TC), the surface morphology, and the crystallinity of the film on thermal annealing temperatures was evaluated. [ABSTRACT FROM PUBLISHER]

In order to design antennas for mid-infrared (MIR) hot electron bolometers (HEBs), the surface impedance of Au thin films at cryogenic temperatures was evaluated using Fourier transform infrared spectroscopy with a sample cooling system. We fabricated resonator arrays that were constructed by gold thin film strips. The length, width, and thickness of the resonators were set at 1300, 200, and 55 nm, respectively. As the temperature was lowered, the resonant frequency was shifted to the low-frequency side. By fitting the resonant frequency to simulated results, the corrected surface reactance was established for designing MIR nano-antennas. MIR HEBs with a twin-slot antenna were designed and fabricated using the corrected surface impedance. The design frequency was 61 THz. The HEBs were formed as a superconducting strip with Au antennas and electrodes. Here, the superconductivity under the Au electrodes was suppressed by a Ni thin film. For evaluating the mixer properties of the MIR HEBs, measurement setup without beam splitter was constructed. In this setup, local oscillator power was applied directly to the HEB, and we confirmed that the critical current of the HEB can be reduced to be almost zero by the LO irradiation. The HEB responses with clear polarization dependencies were also observed. [ABSTRACT FROM AUTHOR]

We investigated the suitability of AlN as a buffer layer for NbN superconducting nanowire single-photon detectors (SNSPDs) on GaAs. The NbN films with a thickness of 3.3–20 nm deposited onto GaAs substrates with an AlN buffer layer demonstrate a higher critical temperature, critical current density, and lower residual resistivity in comparison to films deposited onto bare substrates. Unfortunately, the thermal coupling of the NbN film to the substrate weakens. SNSPDs made of 4.9-nm-thick NbN films on buffered substrates (in comparison to detectors made from NbN films on bare GaAs) demonstrate three orders of magnitude lower dark count rates and about ten times higher detection efficiency at 900 nm being measured at 90% of the critical current. The system timing jitter of SNSPDs on buffered substrates is 72 ps, which is 36 ps lower than those on bare substrate. However, a weaker thermal coupling of NbN nanowire to the buffered substrate leads to a latching effect at bias currents > 0.97 I C. [ABSTRACT FROM PUBLISHER]

Introduction: The NBN gene product is part of the MRE11/RAD50/NBN complex, which plays an essential role in genomic stability. In the study we try to answer the question what is the effect of irradiation on DNA synthesis, NBN gene expression and chromosomal stability in cells with homozygous c.657-661del, and heterozygous c.657-661del, p.I171V and p.R215W NBN gene mutations.Material and Methods: Immortalized B-lymphocytes with NBN gene mutations were X-ray irradiated at doses of 1, 2, 5 and 8 Gy/min. Radioresistant DNA synthesis rate and the percentage of cells in phase S was analyzed by 3H thymidine and BrdU incorporation assays. NBN gene expression was quantified by real-time PCR with TaqMan fluorescent probe.Results: Increasing the irradiation dose resulted in gradual decrease of 3H thymidine incorporation in all cells, but significantly only in homo- and heterozygous c.657-661del cells (p-values < 0.0001). After irradiation the relative expression of NBN was significantly higher in homozygous c.657-661del and heterozygous p.R215W cells as compared to heterozygous c.657-661del, p.I171V and control cells (p < 0.01). All cells with NBN gene mutations showed significantly higher total number of chromosomal aberrations per metaphase as compared to control cells, with the highest number of aberrations in homozygous c.657-661del cells (p < 0.001).Conclusions: The results obtained indicate that homozygous c.657-661del mutation affects cell sensitivity to irradiation. Moreover, homozygous variant is associated with disturbance in the activation of cell cycle checkpoints and with defects in DNA repair. In turn, heterozygous c.657-661del, p.R215W and p.I171V mutations do not substantially alter the radiosensitivity. [ABSTRACT FROM AUTHOR]

• Superconducting NbN has low spin–orbit coupling and makes a good candidate to perform meservey-tedrow measurements. • Using the robust surface oxide, tunnel junctions on NbN can be fabricated using a facile process without lithography. • Due to the high t c of NbN (∼16.5 K), one can perform the spin polarization measurement of ferromagnets at temperatures at high as 1.57 K. We report a two-step process for the fabrication of superconductor-insulator-normal metal tunnel junctions using NbN as the superconducting electrode and its surface oxide as the insulating tunnel barrier, and investigate its efficacy in measuring spin-polarisation of ferromagnets using the Meservey-Tedrow technique. We observe that for NbN film thickness below 10 nm, under the application of parallel magnetic field, the superconducting density of states show clear "Zeeman" splitting into spin-up and spin-down sub-bands. Tunnelling measurements on devices where ferromagnetic Co is used as the normal electrode shows that these devices can be used to measure spin polarisation of a ferromagnet at temperatures up to 1.6 K. The simplicity of our fabrication process makes NbN a very attractive candidate for spin polarisation measurements. Some limitations of this process are also discussed. [ABSTRACT FROM AUTHOR]

Transition metal nitride thin films such as TiN are necessary as conducting electrodes in memory and transistor devices. Due to their high work function (> 4.7 eV), NbN thin films have recently attracted attention to replace TiN thin films as capacitor electrodes using atomic layer deposition (ALD) process in dynamic random access memories (DRAMs) to reduce leakage currents in the capacitors. Unfortunately, the NbN ALD process using NbCl 5 and NH 3 as the Nb precursor and nitrogen source resulted in a high resistivity (> 500 μΩ·cm) despite its low bulk resistivity (∼10 μΩ·cm at 300 K) because of the residual Cl impurity (> 5%) within the NbN film. In this study, an alternative ALD surface reaction pathway is proposed by introducing H 2 S gas pulses between the NbCl 5 and NH 3 pulse steps to lower the Cl impurity concentration. Using the alternative ALD reaction, the residual Cl concentration was reduced below 1.5% (decrease by > 50%) at the specific ALD deposition temperature of 673 K. Finally, this reaction produced a greater decrease in the resistivity (> 30%) of NbN thin films than the conventional NbN ALD at 673 K. • Alternative reaction in atomic layer deposition (ALD) for NbN thin film growth. • Introduction of H 2 S in the NbN ALD process using NbCl 5 and NH 3. • Reduction of Cl impurity concentration by using the alternative ALD reaction. • Decrease in the resistivity of the NbN thin films owing to the Cl impurity decrease. [ABSTRACT FROM AUTHOR]

Superconductivity and the normal-state properties of NbN films can be tuned in a wide range, supplying a suitable platform to investigate the systematical evolution of the superconducting performances. Herein, we report the upper critical field of NbN films in both the vertical (B ⊥ film) and parallel (B ∥ film) orientations over a wide temperature range. Eight samples with the superconducting critical temperature T c ranging from 2.5 K to 9.8 K are studied. It is found that the magnitudes of the upper critical field in the parallel direction (B c 2 ∥) exceeds the paramagnetic limiting field B p in the zero-temperature limit, while the perpendicular one (B c 2 ⊥) is closely approaching B p. The temperature dependent B c 2 ⊥ can be described by the extended Werthamer–Helfand–Hohenberg (WHH) model considering the Pauli spin paramagnetism. Meanwhile, the B c 2 ∥ − T data shows the feature of two-dimensional superconductivity in the temperature range near T c. Our results show that the Pauli paramagnetic effect is greatly enhanced with the decrease of T c. The evolution of the obtained Maki parameter with other parameters are discussed to reveal the characteristics of the Pauli paramagnetic effect in this system. • B c2 || exceeds the Pauli-limiting field B p , while B c2 ${\perp }$ is closely approaching B p. • B c2 ${\perp }$ - T curves can be described by WHH model consideringPauli paramagnetic effect. • The Pauli paramagnetic effect is greatly enhanced with the decrease of T c. [ABSTRACT FROM AUTHOR]

We present the first measurements of x -ray photoelectron spectroscopy (XPS) core level binding energies (BE:s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN’s) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400 °C by reactive dc magnetron sputtering from elemental targets in Ar/N 2 atmosphere. For XPS measurements, layers are either (i) Ar + ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF-E ERDA), Rutherford backscattering spectrometry (RBS), and x -ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al Kα radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar + ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ . In addition, the N/metal concentration ratios are found to be 25–90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE:s extracted from capped TMN films, thus characteristic of a native surface, show a systematic trend, which contrasts with the large BE spread of literature “reference” values. Hence, non-destructive core level XPS employing capping layers provides an opportunity to obtain high-quality spectra, characteristic of virgin in situ grown and analyzed TMN films, although with larger versatility, and allows for extracting core level BE values that are more reliable than those obtained from sputter-cleaned N-deficient surfaces. Results presented here, recorded from a consistent set of binary TMN’s grown under the same conditions and analyzed in the same instrument, provide a useful reference for future XPS studies of multinary materials systems allowing for true deconvolution of complex core level spectra. [ABSTRACT FROM AUTHOR]

Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarised parallel with and perpendicular to the direction of applied magnetic field. [ABSTRACT FROM AUTHOR]

Ongoing studies to characterize and improve the radiation tolerance of the quantum efficiency (QE) in III-V-based, unipolar barrier infrared detectors, such as nBn’s, require accurate knowledge of the detector QE damage factor. Here, results of such studies are described which demonstrated that a QE damage factor determined from the slope of the apparent linear relationship between inverse QE and proton fluence was more accurate than the previous method. Comparatively, the new approach did not require truncating the fitting range and it more clearly demonstrated the expected monotonically decreasing relationship between QE damage factor and relative amount of absorber layer grading in nBn detectors. Simulations were then done which supported this finding. Results from a similar study of HgCdTe photodiodes indicated an identical linear behavior which then abruptly saturated at higher proton fluence. Additional simulation suggested photo-collection here also relied on drift, which thereby limited the total effects of displacement damage on QE. [ABSTRACT FROM PUBLISHER]