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Crystal structure of the homologues series of (InGaZnO3)m(ZnO)n.

The establishment of a reliable method for the growth of bulk In–Ga–Zn–O single crystals is important not only to investigate the fundamental and peculiar properties specific to this material but also for its development for novel functional devices. Large bulk single crystals of InGaZnO4 have been successfully grown using an optical floating zone method under a flow of dry-air at high-pressure. The stoichiometric InGaZnO4 single crystals were obtained at a gas pressure of 0.9 MPa using a feed rod with a Zn-rich composition, where the lattice constants are a = 3.2990(4) A and c = 26.018(3) A as the hexagonal expression for the rhombic system (space group Rm, No. 166). The as-grown single crystals exhibit a blueish colour, but become transparent after annealing in oxygen. Upon post-annealing, the carrier density, the conductivity in the ab-plane and the mobility at room temperature changes in the range from ∼1020 to ∼1017 cm−3, from ∼2000 to ∼1 S cm−1, and from ∼100 to ∼10 cm2/(Vs), respectively. In addition, we found that the conductivity along the c-axis is much lower than that of the ab-plane in InGaZnO4 single crystals, and that the anisotropy increases with decreasing carrier density.

Phase relations in the pseudo ternary systems In2O3-TiO2-ZnO, In2O3-TiO2-CoO and In2O3-TiO2-NiO at 1200 °C in air were determined by means of a classic quenching method. In6Ti6BO22 (B: Zn, Co and Ni) which has the monoclinic In(Fe1/4Ti3/4)O27/8-type of structure with a 4-dimensional super space group exists in a stable form. There exist homologous phases In1+x(Ti1/2Zn1/2)1−xO3(ZnO)m (m: natural number, 0 3 ¯ m (No. 166) for m = odd or P63/mmc (No. 194) for m = even in space group. Lattice constants for each of the homologous compounds as a hexagonal setting and In6Ti6BO22 as the monoclinic system were determined by means of the powder X-ray diffraction method at room temperature. The temperature dependence of resistivity for In1+x(Ti1/2Zn1/2)1−x(ZnO)4 (0.15 ≤ x ≤ 1) showed semiconducting-like behavior for all samples examined at T(K) = 2–300. The resistivity increased systematically with decreasing x (0.7 ≤ x ≤ 1), and it was found that samples where x ≤ 0.7 became insulators. The optical band gap Eg (eV) of In1+x(Ti1/2Zn1/2)1−x(ZnO)4 has been estimated from the diffuse reflection spectra for the whole range of x (0.15 ≤ x ≤ 1). A minimum value of 2.0717 eV for x = 1 and a maximum one of 3.066 eV for x = 0.15 were observed. Dependence of the crystal structures of the InAO3(BO), In(Ti1/2B1/2)O3(B′O) and stability of In6Ti6BO22 upon the constituent cations in the pseudo quaternary system In2O3-TiO2-A2O3-BO (A: Fe, Ga and Cr; B, B′: Mg, Zn, Co, Ni, Ca and Sr) were discussed in terms of their ionic radii and site preference effects.

Superconductivity is achieved in Nd1-xCexOBiS2 via electron doping using mixed-valence Ce ions. Single crystals with x = 0.2, 0.3, 0.4, and 0.5 are generated using a CsCl flux method. Plate-like single crystals with dimensions of 0.8 0.8 0.2 mm3 were obtained. The magnetic susceptibility chi(T) indicates large diamagnetism, and the electrical resistivity rho(T) indicates zero resistivity. The maximum value of Tc is observed at 4.7 K in Nd0.8Ce0.2OBiS2 from chi(T). From the rho(T) measurements taken in several magnetic fields, the upper critical field mu0Hc2(0) is estimated to be about 12 and 0.34 T for the ab- and c-planes, respectively. We redetermined mu0Hc2(0) of NdO0.7F0.3BiS2, as about 35 and 0.78 T for the ab- and c-planes, respectively. The anisotropic parameter is estimated to be about 35 for Nd0.7Ce0.3OBiS2 and 45 for NdO0.7F0.3BiS2. The mu0Hc2(0) of Nd0.7Ce0.3OBiS2 is approximately two times smaller than that of NdO0.7F0.3BiS2, although the difference of Gamma is approximately 10., 5 pages, 4 figures

The aim of this study was to investigate the efficacy of concurrent treatment with vitamin K2 and risedronate compared with treatment with risedronate alone in patients with osteoporosis and to explore subsets of patients for which concurrent treatment is particularly efficacious. Women with osteoporosis aged 65 years or older were recruited from 123 institutes in Japan and allocated to take either vitamin K2 (45 mg/day) and risedronate (2.5 mg/day or 17.5 mg/week) or risedronate (2.5 mg/day or 17.5 mg/week) alone. The primary end point was the incidence of any fracture (vertebral and nonvertebral). The secondary end points were bone mineral density, height, undercarboxylated osteocalcin concentration, quality of life, and safety. Over a 2-year follow-up, vertebral or nonvertebral fractures occurred in 117 or 22 sites respectively among 931 patients in the risedronate and vitamin K2 group and in 104 or 26 sites respectively among 943 patients in the risedronate alone group. The rates of any incident fracture were similar between the two groups (incidence rate ratio 1.074, 95 % confidence interval 0.811-1.422, p = 0.62), implying that the primary end point was not met. There were no differences in the degree of increase in bone mineral density between the two groups. Undercarboxylated osteocalcin concentration decreased from 5.81 ± 3.93 ng/mL to 2.59 ± 1.52 ng/mL at 6 months in the risedronate and vitamin K2 group, whereas the change in the risedronate alone group was minimal (from 5.96 ± 4.36 ng/mL to 4.05 ± 3.40 ng/mL at 6 months) (p

Crystals of the quaternary compound In1-xGa1+xO3(ZnO)0.5 were grown by the optical floating-zone method using a mirror furnace with halogen lamps as heat source. X-ray diffraction (XRD) and electron diffraction yielded a hexagonal crystal system and the space group P 6 3 / m m c (No. 194). Structure refinement from single crystal XRD data at −90 °C (a ​= ​3.3137(1) A; c ​= ​29.523(1) A; wR2: 0.054) revealed a structure isotypic to YbFeO3(FeO)0.5 and consists of three different alternating layers: (i) layer of edge-sharing InO6 octahedra, (ii) a pair of two layers of corner-sharing (Ga/Zn)O4 tetrahedra corresponding to wurtzite structure type, and (iii) a layer of GaO5 trigonal-bipyramids (tbp). The polyhedra of layers (ii) and (iii) share corners with the InO6 octahedra, resulting in inverted orientations of the two (Ga/Zn)O4 layers in the wurtzite type region. Additionally, atomic resolution imaging in the electron microscope proves a perfect periodic stacking of the atomic layers. The analysis of individual crystals revealed an excess of Ga expressed by the composition range In1-xGa1+xO3(ZnO)0.5 with 0.20 ​≤ ​x ≤ 0.82, determined by energy dispersive X-ray spectroscopy (EDXS). Consequently, the octahedral site is occupied with In and Ga in a ratio of In:Ga ​= ​0.80:0.20 to 0.18:0.82, assuming that the tbp sites are only occupied by Ga. The transparent crystals as-received from floating-zone growth had a blueish color and became colorless after annealing at 1000 ​°C for 10 ​h in air. The as-prepared crystals are oxygen deficient and contain unpaired electrons (color centers) at vacant oxide sites proven by electron paramagnetic resonance with g-value of ca. 2.

We synthesize a new titanium-oxide compound AlTi2O5 with pseudobrookite-type structure. The formal valence of Ti is 3.5+ that is the same as the Magneli compound Ti4O7 and the spinel compound LiTi2O4. AlTi2O5 exhibits insulating behavior in resistivity. Using experimentally determined crystal structure, we perform the first-principles calculations for the electronic structures. Experimentally suggested random distribution of Al and Ti is not the origin of the insulating behavior. The Fermi surfaces for nonrandom AlTi2O5 show cylindrical shapes reflecting a layered structure, which indicates a possible nesting-driven order. Constructing a tight-binding model from the first-principles calculations, we calculate the spin and charge susceptibilities using the random phase approximation. We suggest possible charge-density-wave state forming Ti3+ chains separated from each other by Ti4+ chains, similar to the low-temperature phase of Ti4O7., Comment: 8 pages, 9 figures

We present the first experimental evidence for metallicity, superconductivity (SC) and the co-existence of charge density waves (CDW) in the quasi-one-dimensional material HfTe3. The existence of such phenomena is a typical characteristic of the transition metal chalcogenides however, without the application of hydrostatic pressure/chemical doping, it is rare for a material to exhibit the co-existence of both states. Materials such as HfTe3 can therefore provide us with a unique insight into the relationship between these multiple ordered states. By improving on the original synthesis conditions, we have successfully synthesised single phase HfTe3 and confirmed the resultant structure by performing Rietveld refinement. Using low temperature resistivity measurements, we provide the first experimental evidence of SC at ~1.4 K as well as a resistive anomaly indicative of a CDW formation at ~82 K. By the application of hydrostatic-pressure, the resistivity anomaly shifts to higher temperature. The results show that HfTe3 is a promising new material to help study the relationship between SC and CDW., 9 pages, 4 figures, includes supplementary information

Terahertz (THz) radiation is in powerful region of electromagnetic spectrum because of prosperous application areas yet deficiency still exists about sources and detectors in despite of improvements of the research field in this range. This gap can be filled by focusing on development of THz detectors. Therefore, bolometers were preferred through many detectors due to detection sensitivity above 1 THz. In this study, Bi2Sr2CaCu2O8+δ (Bi2212) single crystals were used to fabricate THz bolometric detector. Bi2212 single crystals were transferred on sapphire substrate by cleavage process and e-beam lithography and ion beam etching were used to fabricate the microchip clean room facilities. Custom-designed cryogenic cryostat was used for a-b axis electrical and THz response measurements with liquid nitrogen cooled system. After electrical measurements, Bi2212 microchips detected the signals using Stefan-Boltzmann Lamp and response time were calculated. This study have shown with our experimental results that Bi2212 single crystals are potential candidates for THz bolometric detectors.

Assessment of vertebral fracture is critically important for the diagnosis and treatment of osteoporosis. This study aimed to clarify the effectiveness of the semiquantitative (SQ) method in the assessment of vertebral fractures in Japanese clinical practice. Forty-four physicians (seven experts and 37 nonexperts) assessed the spinal radiographs of 40 patients participating in the Adequate Treatment of Osteoporosis (A-TOP) Japanese Osteoporosis Intervention Trial (JOINT)-02 at the baseline, 12 months, and 24 months using the SQ method. The proportion of diagnosed fracture cases per spine was higher in the nonexpert group than in the expert group at each time point, and was especially high in the upper thoracic spine (T4-T6). The least mean squares spinal fracture index was significantly higher in the nonexpert group than in the expert group for all time points. The kappa statistics were also higher in the expert group than in the nonexpert group for all vertebral levels at all time points. Assessment of vertebral fractures using the SQ method tended to be overestimated by nonexpert physicians compared with the experts, with poor nonexpert interobserver reliability and well-matched expert interobserver reliability. Conscious efforts to avoid overestimation and to obtain higher reliability with the SQ method should be made to achieve more precise diagnoses and treatment of osteoporosis in Japanese clinical practice.

We measured tunneling conductances on an under-doped trilayer cuprate Bi2.1Sr1.9Ca2Cu3O10+≏ (Bi2223) with TC ∼ 101 K by a point contact method, which has three CuO2 planes in a unit cell. The tunneling conductances on Bi2223 exhibited two sizes of gaps originated from outer and inner CuO2 plane (OP and IP). The estimated size of superconducting gap from OP ΔOP is 34 ± 6 meV, and the ΔIP from IP is 51 ± 5 meV, respectively. We also observed tunneling conductances which simultaneously displayed two superconducting peaks of OP and IP. Moreover, we propose the model of two superconductor-insulator-normal metal junctions which exhibit two sizes gaps of OP and IP.

We present the first experimental evidence for metallicity, superconductivity (SC) and the co-existence of charge density waves (CDW) in the quasi-one-dimensional material HfTe3. The existence of such phenomena is a typical characteristic of the transition metal chalcogenides however, without the application of hydrostatic pressure/chemical doping, it is rare for a material to exhibit the co-existence of both states. Materials such as HfTe3 can therefore provide us with a unique insight into the relationship between these multiple ordered states. By improving on the original synthesis conditions, we have successfully synthesised single phase HfTe3 and confirmed the resultant structure by performing Rietveld refinement. Using low temperature resistivity measurements, we provide the first experimental evidence of SC at ~1.4 K as well as a resistive anomaly indicative of a CDW formation at ~82 K. By the application of hydrostatic-pressure, the resistivity anomaly shifts to higher temperature. The results show that HfTe3 is a promising new material to help study the relationship between SC and CDW.

Concurrent treatments with bisphosphonates and vitamin K are promising given that bisphosphonates possibly interfere with vitamin K activation. This is a prospective, multi-center, open-labeled, randomized trial of the efficacy of concurrent treatment with vitamin K2 and risedronate compared with risedronate alone and to explore subsets of patients for which concurrent treatment is particularly efficacious (trial identification number UMIN000000991). Inclusion criteria are women who meet the criteria for pharmacological therapy for osteoporosis, aged ≥65 years, have any of pre-specified risk factors, can walk unassisted, and are able to answer questionnaires. Exclusion criteria are prior warfarin use, secondary osteoporosis or non-osteoporotic metabolic bone diseases, contraindication for vitamin K2 and risedronate, hyper- or hypoparathyroidism, mental disorders, prevalent vertebral fracture at ≥6 sites, severe degenerative spinal deformation between T4 and L4, serious heart, liver, or kidney disease, or bisphosphonate use within the previous 6 months. Patients were recruited from 123 institutes between January 2008 and February 2010, and allocated to vitamin K2 (45 mg/day) and risedronate (2.5 mg/day or 17.5 mg/week) or risedronate alone (2.5 mg/day or 17.5 mg/week) groups. Primary endpoint is a vertebral or non-vertebral fracture. Secondary endpoints are bone mineral density, height, undercarboxylated osteocalcin, JOQOL, EQ-5D and safety. A sample size of 910 subjects per group and 2-year follow-up will provide 80 % power to detect 35 % risk reduction for fracture, with a two-sided significance level of 5 %. Subgroup analysis stratified to adjustment factors for random allocation, body mass index, 25-hydroxyvitamin D, estimated glomerular filtration rate, grade of vertebral fracture, JOQOL, EQ-5D, and co-morbidity is pre-specified.

In this study, we developed a microbolometer chip fabricated from high temperature superconducting Bi2Sr2CaCu2O8+δ (Bi2212) single crystals for the terahertz (THz) detection. For the manufacturing of the microbolometer chips, Bi2212 single crystals were transferred on substrate in the thin film like form and electron beam lithography, ion beam etching techniques were used. Resistance versus temperature behavior of the bolometer chips were performed by four probe technique in liquid nitrogen cryostat. Bi2212 microchips were integrated and characterized using in our custom-designed cryogenic bolometer system instead of expensive and massive cooling systems. The fabricated microchips significantly detected signals from the Stefan-Boltzmann lamp which includes a portion of THz radiation. The detected power and response time were studied for Bi2212 thin film like microbolometer chips. Our results demonstrated the feasibility of improved Bi2212 microchips could be used for bolometric detection for THz applications., Ministry of Science, Industry and Technology (SANTEZ 1386.STZ.2012-1)

The aim of this study was to investigate the efficacy of concurrent treatment with vitamin K

TlFe2Se2-δ was synthesized by a self-flux method with excess amount of selenium. Elemental analysis using energy-dispersive X-ray spectroscopy estimates the deficiency δ at about 0.5. The magnetic susceptibility reveals an antiferromagnetic transition at TN ≈ 475 K. The resistivity exhibits a semiconducting behavior with an activation energy, EA = 0.04 eV. There is a clear anomaly in the resistivity at TN, indicating a strong interplay between magnetism and electric conduction.

We performed the electrical resistivity and thermoelectric power measurements of the polycrystalline La0.8Ti0.2OBi(S1-xSex)2. The electrical resistivity of La0.8Ti0.2OBi(S0.7Se0.3)2 at room temperature dramatically decreases, and the temperature dependence shows metallic-like behavior. From the electrical resistivity, superconductivity was not observed in La0.8Ti0.2OBi(S1-xSex)2 above 2.8 K. The value of thermoelectric power S(300 K) of La0.8Ti0.2OBiSSe was about -65 μV/K, which is comparable to that of the polycrystalline LaOBiS2. The value of S(300 K) of La0.8Ti0.2OBiS2 was about -115 μV/K. These power factors are relatively smaller than that of the polycrystalline LaOBiSSe.

Electrical resistivity of LaO0.5F0.5Bi(S0.9Se0.1)2 have been measured at a temperature range of 2.8 ∼ 300 K by applying several hydrostatic pressures. Pressure-induced superconducting phase was observed above a pressure P of 0.85 GPa and Tc increased from 2.86 K to 8.42 K. The sudden increase of Tc in LaO0.5F0.5Bi(S0.9Se0.1)2 results from the structural phase transition from tetragonal (P4/nmm) to monoclinic (P21/m). Structural phase transition pressure Pc of LaO0.5F0.5Bi(S0.9Se0.1)2 is higher than that of LaO0.5F0.5BiS2. The increase of Pc is ascribed to the suppression of the displacement parameter of the in-plane chalcogen site induced by chemical pressure of Se-substitution.

The aim of osteoporosis treatment is to prevent future fractures. Although concurrent treatment has been used very frequently for osteoporosis in clinical practice, there are no data on accurate and verified effectiveness of concurrent treatment for fracture prevention in patients with osteoporosis. To clarify the clinical usefulness of concurrent treatment, the Japan Osteoporosis Society has authorized the establishment of the A-TOP (Adequate Treatment of Osteoporosis) research group. The objective of this research is to establish a design for a clinical trial to prove whether concurrent treatment using both alfacalcidol (1-alpha-hydroxycholecalciferol) and alendronate is more effective as compared to treatment using alendronate alone in terms of fracture prevention. The present study was named JOINT (Japanese Osteoporosis Intervention Trial) and is based on a method using national, prospective, randomized, open-labeled, blinded endpoints focusing on postmenopausal osteoporosis with a high risk for fracture. The patients were mainly selected by practitioners and allocated randomly by a central registration system into two groups, of which one received 5 mg/day of alendronate alone, and the other received 1 μg/day of 1-alpha-hydroxycholecalciferol (alfacalcidol) in addition to the alendronate. The endpoints focused primarily on fracture prevention, and the patients' quality of life (QOL) and change in body height, as well as adherence and the adverse events of the treatments were evaluated secondarily. To obtain sufficient statistical power in the events during a 2-year observation period, the patients who are expected to have higher risk were selected to participate in this study, and it was decided that the final plan would involve 890 patients per group (two-sided alpha = 0.05, power = 0.8). Data collection began in November 2003. Correspondence regarding the registration of the investigator and the progress of the study was conducted through a web system from the Public Health Research Foundation to practitioners.

We report the tunneling spectroscopy of an iron-based oxypnictide NdFeAsO0.7 with T C=51 K, measured by a mechanical point contact technique. Mainly two kinds of tunneling spectra have been observed reproducibly. One is tunneling conductance displaying sharp superconducting gap peaks at 6.0±1.0 mV, in which hump (or kink) structures are also observed at 20–30 mV. Another is that showing dominantly the larger superconducting gap Δ L with sharp conductance peaks at 14±1.0 meV, in which the trace of a smaller gap (Δ S=5–7 meV) is simultaneously observed. Our results give direct evidence for the existence of multiple gaps in the quasiparticle excitation spectrum of this multiband system, although the origin of the hump at 20–30 mV is still unclear.

We have developed a new three-dimensional stacking technology using the wafer-to-wafer stacked method. Electrical conductivity between each wafer is almost 100% and contact resistance is less than 0.7Ω between a through-silicon via (TSV) and a microbump. We have also created a prototype of a three-layer stacking device using our technology, where each wafer for the stacking is fabricated by using 0.18um CMOS technology based on 8-inch wafers. The device is operated by two times the frequency of the multichip module (MCM) device case using a two-dimensional device with identical functions and minimally different power consumption. The yields obtained from the results comprising all functional tests are over 60%.

We report the tunneling conductance on a quadruple-layered cuprate, Ba 2 Ca 3 Cu 4 O 8( O 1-x F x)2 (2x~1.4, Tc~100 K ) that includes inequivalent outer (OP) and inner (IP) CuO 2 planes in a unit cell. Typical tunneling conductance displays the spectral dip structures as well as the superconducting gap (SCG) with clear coherence peaks. However we sometimes observe a pseudogap (PG) like structure without coherence peak at 4.2K. The magnitude of PG at 4.2K is larger than that of SCG at 4.2K and its conductance curve displays a faint structure at low energy. Therefore its origin would be different from that of small-PG observed at above Tc. In addition, we find that there are two kinds of SCGs that originate from IP and OP, and this result suggests that the superconducting property at IP is different from that at OP because of the imbalance of doped carrier between IP and OP. The observation of large PG at low temperature suggests the existence of some form of hidden ordered state at Tc and it would coexist with superconductivity.

The rapid increase in applications of terahertz waves requires new techniques to obtain continuous wave terahertz sources. Mesa structures fabricated from high-Tc superconductor Bi2Sr2CaCu2O8+δ (Bi2212) single crystal have been observed as an intense, coherent, continuous electromagnetic wave source in the terahertz (THz) frequency region. However, in order to produce coherent radiation with high applicable power, we need large mesa structures that enter a collective electromagnetic state in which their oscillations are largely synchronized in phase. On the other hand, large mesa structures cause a heating problem. In this study, we report on the critical current density dependence of mesa area and the crystal inhomogeneity to understand heating problems in large area mesas for terahertz radiation. Since the doping dependence of Bi2212 is an important parameter, the as-grown Bi2212 crystals were heat-treated at various temperatures under vacuum conditions. We have fabricated triple mesa structures from Bi2212 single crystal using e-beam lithography and argon ion beam etching techniques with same area and with different area on the same chip. We investigated and compared characteristics of triple mesas which are on the same chip and next to each other. In this way, we searched the crystal inhomogeneity in triple mesa structures and studied the critical current density dependence of mesa area to obtain high emission power for the THz radiation. Our experimental results clearly show that the Josephson critical current density is decreasing when the area of mesa is increasing. © 2015 Elsevier Ltd. All rights reserved., TUBITAK (110T248); SANTEZ (1386.STZ.2012-1)

Microcrystalline silicon carbide (@mc-SiC) has several applications, such as solar cells, light-emitting diodes and as optical coating for solar cells. Hydrogenated amorphous silicon carbide (a-SiC:H) grows by plasma enhanced CVD, even under hydrogen diluted conditions. High concentration of atomic hydrogen from catalytic CVD could promote lower temperature growth of @mc-SiC under the same conditions as a-SiC:H without plasma. In the present study, @mc-SiC films have been successfully grown by catalytic CVD (hot-filament catalysis) from monomethylsilane and hydrogen on (100) silicon substrates maintained at 300^oC. The optimal chamber pressure is 1.0Torr and the optimal concentration of monomethylsilane in the hydrogen carrier gas is 1%. FTIR spectra of films obtained under these conditions show strong Si-C peaks.

Films of a-SiC:H grown on Si single crystal (1 0 0) by plasma-enhanced chemical vapor deposition (PECVD) are analyzed by Fourier transform infrared (FTIR) spectroscopy. PECVD is performed using a single monomethylsilane (CH3SiCl3) source with hydrogen carrier gas. The hydrogen bond content of the films is determined from the FTIR spectra and compared with the carbon and silicon bond contents as an investigation of the growth process during the atom incorporation phase. The silicon bonding environment is also investigated based on the shift of the FTIR peak of Si–C and Si–H bonds. It is found that the hydrogen bonds of the films is proportional to the square of plasma power density, explainable as due to a combination of two one-step reactions producing non-emissive atomic hydrogen and SiH2. The shift of the SiHn ( n = 1 , 2 ) peak reveals that the atoms nearest Si in the film are replaced by Si or H atom from C in CHn with increasing hydrogen content. A scheme for film growth in this system is then proposed based on the present and previous findings.

We present point contact tunneling spectroscopy measured on TlBa 2 Ca 2 Cu 3 O 10-δ ( Tl 1223) with three CuO 2 planes in a unit cell. Our samples of Tl 1223 with Tc~91 K are heavily overdoped at the outer CuO 2 planes (OP), but slightly underdoped at the inner CuO 2 planes (IP). The tunneling conductances on Tl 1223 exhibit two kinds of gaps that originate from crystallographically inequivalent IP and OP. The overall spectral shape of tunneling conductance for Tl 1223 is consistent with that observed on a bilayer Bi 2 Sr 2 CaCu 2 O 8+δ, that is, unusual peak-dip-hump (PDH) structures are observed. The origin of PDH structures is controversial, but these results, especially, the observation of PDH for trilayer Tl 1223 in which interlayer effects should be quite different from that in bilayer, put severe constraints on any theoretical model for the origin of these structures.

Point contact tunneling data are reported in a multilayered high-T c cuprate (Cu,C)Ba 2 Ca 3 Cu 4 O 12+δ with T c = 117 K . The tunneling spectra in the superconducting state (T ≪ T c ) display spectral features such as well-defined superconducting gap peak at ±Δ as well as dip-hump structures beyond the peaks. In some cases, the spectra with two-gaps have been observed, indicating the coexistence of two inequivalent superconducting layers. The statistical distribution of superconducting gap magnitude suggests two distinct kinds of superconducting gaps that may originate from two inequivalent CuO 2 planes, a characteristics of multilayered cuprates with n ≥ 3.

Tunneling measurements are performed on Ca-rich single crystals of Bi2Sr2CaCu2O8+d (Bi2212), with various oxygen doping levels, using a novel point contact method. At 4.2 K, SIN and SIS tunnel junctions are obtained with well-defined quasiparticle peaks, robust dip and hump features and in some cases Josephson currents. The doping dependence of tunneling conductances of Ca-rich Bi2212 are analyzed and compared to stoichiometric Bi2212. A similar profile of energy gap vs. doping concentration is found although the Ca-rich samples have a slighly smaller optimum Tc and therefore smaller gap values for any doping level. The evolution of tunneling conductance peak height to background ratios with hole concentration are compared. For a given doping level, the Ca-rich spectra showed more broadened features compared to the stoichiometric counterparts, most likely due to increased disorder from the excess Ca. Comparison of the dip and hump features has provided some potential insights into their origins.

Proceedings of the Conference on Spectroscopies in Novel Superconductors, Break-junction tunneling data are reported in Bi2Sr2CaCu2O8+δ over a wide range of hole concentration from underdoped to overdoped. The strong conductance peaks in the superconducting state reveal a single gap consistent with d-wave symmetry. In addition, sharp dips are observed at a voltage, Ω/□, measured with respect to the gap edge. These features are shown to be reproduced in other junction types from the literature including atomically resolved STM and □-axis mesas, establishing their intrinsic character. Trends are observed with doping and temperature which link the dip to the resonance spin excitation and indicate that the quasiparticles are strongly coupled to this mode.

We report tunneling spectroscopy of superconductor-insulator-superconductor break junctions on heavily overdoped Bi2Sr2CaCu2O8 + δ with Tc = 56 K. At T Tc. Above Tc, the tunneling conductance shows a flat background without any indication of a pseudogap near the Fermi level.

Films of a-SiC:H were deposited on Si (1 0 0) substrates by plasma chemical vapor deposition from monomethylsilane. The growth kinetics is discussed on the basis of in situ optical emission spectroscopy (OES) and absorption spectroscopy. The film has near-stoichiometric composition and the growth rate increases slightly with increasing plasma electron density. The OES spectra indicate the presence of H, H 2 , and SiH, and an SiH 2 band is observed in the absorption spectra. It is considered that the SiH 2 concentration determines the growth rate. The spatial distribution of atomic hydrogen and SiH according to OES spectra indicates that the reaction species in the plasma reach the substrate by diffusion.

A comparison of two kinds of source materials is made with regard to the growth kinetics of hydrogenated amorphous silicon carbide films using the RF plasma CVD system with parallel electrodes. The two kinds of sources, methyltrichlorosilane and monomethylsilane, are molecules that include one atom each of carbon and silicon. They are used with a hydrogen carrier gas. In the methyltrichlorosilane–hydrogen system, a possible precursor to silicon carbide is SiCl 2 , and the silicon/carbon ratio of the films can be greatly changed by adjusting the plasma power. In the monomethylsilane–hydrogen system, SiH 2 is the rate-determining species, and the silicon/carbon ratio of the films can be slightly changed by adjusting the plasma power. The optical emission spectroscopy (OES) intensity distribution suggests that the precursor in both cases migrates to the substrate from the plasma sheath by diffusion.

One of main challenges of 3D-integration is the area overhead which has two main causes: first the huge TSV diameter which is usually in the range of microns, and the second reason is the Keep-Out-Zone (KOZ) overhead due to the high induced thermal stresses during fabrication. The area overhead besides the fabrication process itself inversely affects the overall yield and fabrication cost, so the increase in area will reduce the yield and increase the fabrication cost. In this paper, the effect of KOZ overhead on the overall area, yield, and fabrication cost is investigated. Also various parameters that might change KOZ overhead are examined. We show that the share of area overhead caused by KOZ is considerably higher compared to that of TSVs. Further, the impact of KOZ is considered for obtaining more accurate estimation on W2W overall yield and fabrication cost of a 3D-IC.

Rapid increase in applications of the electromagnetic waves in the terahertz frequency range requires new techniques to obtain continues-wave terahertz radiation sources. It is shown that rectangular shaped mesa structure from Bi2Sr2CaCu2O8+d (Bi2212) is a good source for generation of terahertz radiation. In this study, we have fabricated triple mesa structures using e-beam lithography and argon ion beam etching techniques. Our aim is to find the critical current density dependence of mesa area to obtain maximum emission power for the terahertz radiation.

We present tunneling spectra measured at 4.2 K on several high- T c cuprates including Bi 2+ y Sr 2−( x + y ) La x CuO 6+ δ (Bi2201), Tl 2 Ba 2 CuO y , Bi 2 Sr 2 CaCu 2 O 8+ δ (Bi2212) single crystals, as well as (Cu,C)Ba 2 Cu 3 Cu 4 O 12+ δ polycrystals, using SIN point contact method. All of high quality tunneling conductances on these samples exhibit not only a well-defined superconducting gap peak at Δ but also the high energy features known as dip (hump) at roughly ∼2 Δ (∼3 Δ ). In addition, it is demonstrated that analogous to Bi2212, the superconducting gap in Bi2201 monotonically increases with decreasing hole concentration. It is concluded that the dip and hump features as well as the doping dependence of energy gap are generic to high temperature superconductors.