Search

Solar cell performance at low light intensity is practically important for power generation capacity in the entire life cycle. Our previous study demonstrated that glass frit, which is an indispensable constituent in paste for metallization of the cells, decreases the performance at low light intensity by causing shunts and recombination in the cells. Furthermore, our study has shown that aluminum in silver/aluminum paste for the metallization of n-type solar cells affects the reaction system among silver, glass frit, and silicon substrate during the firing process; as a result, aluminum mitigates shunts and recombination due to the paste. Thus, it can be possible that the aluminum mitigates the degradation of the low light performance due to the glass frit, because it has been reported that the performance of solar cells with low shunt resistance becomes lower at low light intensity. For this reason, in this study, the effects of aluminum on shunts, recombination, and low light performance of the cells due to glass frit are investigated. In conclusion, the aluminum decreases the recombination caused by the glass frit, resulting in mitigation of a decrease in open-circuit voltage and an increase in series-resistance due to the frit; then, the aluminum alleviates the degradation of the solar cell performance due to the frit at low light intensity.

Solar cell performances at low light intensity are practically more important for power generation capacity in the entire life cycle. Previous studies have revealed that efficiency and maximum power of the solar cells with low shunt resistance become lower at the low light intensity. In contrast, our study has demonstrated the effects of paste or glass frit as paste constituents on shunts and recombination, as well as open-circuit voltage of solar cells with floating contact method. However, the effects of the glass frit in the paste on the low light performances of the cells have not been actually clear yet. For this reason, in this study, the effects of the glass frit itself on the low light performances of the cells are investigated. This is because even though the glass frit is an indispensable constituent for silver paste to electrically contact to the solar cells, the effects of the glass frit itself on cell performance have not been clear yet. In conclusion, the glass frit itself makes the solar cell performances lower at the low light intensity, especially open-circuit voltage and fill factor, by causing shunts and recombination, which means that the effects of paste constituents on shunts and recombination are important not only for solar cell performances at 1 sun, but also for the performances at low light intensity.

Silver/aluminum (Ag/Al) paste has been used as metallization for p + emitter of n-type solar cells. Nevertheless, the Ag/Al paste induces junction current leakage or shunting in the solar cells, resulting loss in open circuit voltage (V oc ). However, the details still are not known about how glass frit and aluminum in the paste affect the p + emitter, and result in the electrical losses, respectively. Furthermore, it is not still clear whether and how the aluminum addition induces the electrical losses. In this study, the “floating contact method” proposed by R. Hoenig was applied for the measurement to investigate the respective effect of glass frit and aluminum on the electrical losses. Conductive paste with the glass frit for the p + emitter induces loss in V oc of the cells even if the paste contains no aluminum. The glass frit in the Ag/Al paste induces carrier recombination and significant shunting of p-n junction, but the aluminum in the paste mitigates these electrical losses because of weakening emergence of Ag-crystallites on the p + emitter.

It was found that critical dimensions of high-k/metal gates obey the multivariate linear approximation with the precision of 3σ=±0.86nm, whose explanatory variables are amounts of metal compounds remaining on the plasma reactor walls. To measure their amounts, the authors assumed they are proportional to amounts of atoms sputtered out by Ar plasma and falling onto a Si wafers placed on a wafer stage. In this study, effects of metal compounds of W, Ti, Ta, and Hf, which are used to construct full-metal/high-k gates, were measured. It was found that Ti and Ta compounds dominate the fluctuation of critical dimensions and the dependency of their amount on wafer numbers being etched obeys a simple difference equation. From these results, they can estimate and minimize the fluctuations of critical dimensions in mass fabrications.

This paper describes a fabrication process that uses flash-lamp annealing (FLA) and the characteristics of the CMOS transistors that are constructed with an ultralow-thermal- budget process tuned for 45-nm metal/high-k FETs. FLA enhances the drivability of pFETs with the solid-phase epitaxial (SPE) extension junction, but reducing the thermal budget deteriorates the poly-gate depletion and the electron mobility. Metal gate, however, prevents the depletion problem and leads to higher drain currents and better threshold-voltage (VTH) roll-offs when processed with tilted extension implantation combined with SPE + FLA than when processed with untilted extension implantation combined with spike rapid thermal annealing. Reducing the thermal budget is also effective in obtaining low VTH values in p-metal/HfSiON gate because of the reduced vacancy formation. Moreover, cluster-boron implantation for pFETs has superiority over monomer-boron implantation with Ge postamorphous implantation in terms of VTH roll-offs and Ion-Ioff's if FLA is used as activation. The superior electrical characteristics of full-metal- gate HfSiON transistors whose gate length is less than 50 nm, which are fabricated by using the FLA process, are demonstrated.

In this paper, the impact of gate line edge roughness (LER) on two-dimensional carrier profiles in sub-50-nm n-MOSFETs was directly evaluated. Using scanning tunneling microscopy (STM), it was clearly observed that the roughness of extension edges induced by gate LER strongly depended on the implanted dose, pockets, and coimplantations. Impurity diffusion suppressed by a nitrogen (N) coimplant enhanced the roughness of the extension edges, which caused fluctuations in the device performance. The expected effect based on the carrier profiles measured by STM of the N coimplant on the electrical performance of the n-MOSFETs was verified

After discovering that the annealing-time dependence of the flatband voltage shifts of a p/sup +/-polysilicon gate MOS diode can be attributed to boron activation in polysilicon instead of boron penetration through gate M/sub 2/, we proposed a boron activation model for polysilicon in which the carrier activation is related to the grain size of the polysilicon. Using this model, we analyzed the characteristics of pMOSFETs with polysilicon gates of different grain sizes and found that they depend on the grain size, as expected. Using the model, we quantitatively identified process windows for p/sup +/-polysilicon gate pMOSFETs, assuming that enough boron is activated in the polysilicon without the boron penetrating through the gate SiO/sub 2/.

Cyclooctatin has been isolated from Streptomyces melanosporofaciens MI614-43F2 as part of a program designed to find microorganism-produced inhibitors of lysophospholipase. It was purified by chromatography on silica gel, Capcell Pak C18 (HPLC) and Sephadex LH-20 followed by solvent extraction and then isolated as a colorless powder. Cyclooctatin has the molecular formula of C20H34O3. It is competitive with the substrate, and the inhibition constant (Ki) was 4.8 x 10(-6) M.

Benastatins have been isolated as part of a program designed to find microorganism-produced inhibitors of glutathione S-transferase from Streptomyces sp. MI384-DF12. They were purified by chromatography of reversed-phase silica gel, silica gel and Capcell Pak C18 (HPLC) followed by solvent extraction and then isolated as yellow powders. Benastatins A and B have the molecular formulae, C30H28O7 and C30H30O7, respectively. They were competitive with 3,4-dichloronitrobenzene as the substrate, and the inhibition constants (Ki) of benastatins A and B were 5.0 x 10(-6) and 3.7 x 10(-6), respectively.

We studied the uniformity of native oxide formed on Si(001) surfaces during wet chemical cleaning. Uniformity was determined by surface morphology at the initial stage of photoexcited fluorine etching. Since photoexcited fluorine etches Si 40 times faster than it etches Si oxide, it highlights Si native oxides on a Si surface making them observable by scanning tunneling microscopy or atomic force microscopy. Boiling in a HCl‐H2O2‐H2O (1:1:4) solution formed 30–70‐nm islands of oxides. The regions between the islands were not oxidized. Boiling in NH4OH‐H2O2‐H2O (1:1.4:4) also formed oxide islands 30–70 nm in diameter, but the interisland regions were slightly oxidized. Boiling in a HNO3 solution resulted in a native oxide with pinholes at a density of 5×109 cm−2

This letter discusses the reaction between (001) oriented Si surfaces and photoexcited fluorine gas resulting in the removal of the native Si oxide. For an F2/Ar gas system, the bulk Si was etched in areas where the native Si oxide had been completely removed. However, by using an F2/H2 gas system, only the native Si oxide was removed. We used this method to remove the native Si oxide in Si epitaxial growth. A high‐quality single‐crystal Si film surface was obtained up to a maximum temperature of 600 °C through this Si growth process. We also characterized the etching of a thermal oxide, silicon nitride, and silicon carbide.

This paper deals with the formulation that can analyze vibration noise problems practically in the flexible multibody systems. Many kinds of formulations have been proposed on the flexible multibody systems so far. They are categorized into several groups according to their purposes and coordinate systems. The floating frame of reference formulation is at present the most popular method for general purpose simulations among them. The formulation uses Cartesian coordinates for the position of a body, Euler angles or Euler parameters for the orientations, and modal coordinates for the elastic degrees of freedom. The equations of motion with these different kinds of coordinates are complicated because of coupling between rigid body motion and elastic vibration. On the other hand, the linear theory of elasto-dynamics appears to be simple and could be practical for some limited uses. But it neglects the effect of the elastic deformation on the rigid body motion. In many cases, the effect is significant and essential. In this paper, we propose a new formulation with rigid body modes and a local observer frame (LOF) for large amplitude rigid body motion, and with elastic modes for small amplitude elastic vibration. The LOF is updated properly to compensate the gap between rigid body motion and the LOF motion. The new formulation makes the coupling terms as simple as possible without any loss of the effect of the elastic deformation on the rigid body motion and gives the uniform description in each modal coordinate.

Benastatins have been isolated as part of a program designed to find microorganism-produced inhibitors of glutathione S-transferase from Streptomyces sp. MI384-DF12. They were purified by chromatography of reversed-phase silica gel, silica gel and Capcell Pak C18 (HPLC) followed by solvent extraction and then isolated as yellow powders. Benastatins A and B have the molecular formulae, C30H28O7 and C30H30O7, respectively. They were competitive with 3, 4-dichloronitrobenzene as the substrate, and the inhibition constants (Ki) of benastatins A and B were 5.0 × 10-6 and 3.7 × 10-6, respectively.

New benzo[a]naphthacenequinone metabolites, designated bequinostatins A and B, have been isolated from the culture broth of the benastatin-producing strain Streptomyces sp. MI384-DF12. The structures of bequinostatins A and B were determined by spectral analyses to be 5,6,8,13-tetrahydro-1,6,7,9,11-pentahydroxy-8,13-dioxo-3- pentylbenzo[a]naphthacene-2-carboxylic acid and 2-decarboxybequinostatin A, respectively. Bequinostatin A showed considerable inhibitory activity against human pi class glutathione S-transferase (GST pi).

Benastatin C, a new member of the benastatins, has been isolated from the culture broth of Streptomyces sp. MI384-DF12. The structure of benastatin C was elucidated as 2-decarboxy-benastatin A by NMR studies. Benastatin D, 2-decarboxybenastatin B, was derived from benastatin B. Benastatins C and D showed inhibitory activities against human pi class glutathione S-transferase (GST pi) and excellent stimulatory activities on the murine lymphocyte blastogenesis in vitro.

The biosynthesis of benastatin A, produced by Streptomyces sp. MI384-DF12, has been studied by feeding experiments with 14C- and 13C-labeled compounds followed by measurement of radioactivity and 13C NMR analysis. The results indicate that benastatin A is derived from two methionine units and fourteen acetate units, condensed in the "head-to-tail" fashion of typical polyketide biosynthesis.

Benastatins A and B, new inhibitors of glutathione S-transferase, have been isolated from the culture broth of Streptomyces sp. MI384-DF12. By X-ray crystallography, benastatin A was determined to be 8,13-dihydro-1,7,9,11-tetrahydroxy-13-dimethyl-8-oxo-3-pentyl- benzo[a]naphthacene-2-carboxylic acid. The structure of benastatin B was elucidated by NMR studies.

Nagstatin, a new inhibitor of N-acetyl-beta-D-glucosaminidase (NAG-ase) was discovered in the fermentation broth of Streptomyces amakusaensis MG846-fF3. It was purified by chromatography on Dowex 50W, Avicel and Sephadex LH-20 followed by the treatment of active carbon and then isolated as colorless powder. Nagstatin has the molecular formula of C12H17N3O6. It is competitive with the substrate, and the inhibition constant (Ki) was 1.7 x 10(-8) M.

not Available.

We will give practical and manufacturable solutions for metal gate/dual high-k CMOS fabrication processes with low threshold voltages which are suitable for scaled CMOS device manufacturing.

We studied the characteristics of ultra-shallow junctions (USJ) formed by flash lamp annealing (FLA) to reveal the nature of the dopant activation. We found that FLA is a form of solid phase epitaxial regrowth(SPER), employing high temperatures and short (mili-second) times. This achieves higher dopant activation than obtained in SPER.

not Available.

We have established a comprehensive understanding of the PBTI and NBTI reliability of high-k/metal gate stacks. PBTI is found to exhibit a universal relationship, in terms of fast transient carrier traps and stress voltage, due to the formation of positive oxygen vacancies. The use of metal gates for Tinv scaling is promising for the improvement of drain current without PBTI lifetime degradation. However, in the case of NBTI, interface state degradation becomes more serious with Tinv scaling. Thus, the use of a high quality interfacial layer, such as a wet oxide interface, is a promising solution for the improvement of NBTI lifetime.

A simple fabrication process has been demonstrated for metal/high-k gate-first CMOS with a single work-function control layer of TaSiN/TaSix accompanied with selective substrate F implantation. Sub-1nm EOT HfSiON gate dielectrics with high-mobility were used, having been subjected to successful suppression of interfacial layer growth during processes. Sufficiently low Vth of 0.39 V and -0.38 V for low- standby-power (LSTP) applications were obtained for nFET and pFET, respectively. A high electron mobility of 213 cm2/Vs at Eeff=1.0 MV/cm was maintained, due to the double nitridation barrier effects of TaSiN/TaSix. Hole mobility enhancement and NBTI improvement were also obtained by F implantation, even in metal gate pFETs.

TaSixNy has been examined as a metal gate material for n- MOSFETs of the future. In order to control the composition of the TaSixNy film, a CVD method has been newly developed, using a commercial-based 300mm machine. The CVD film composition can be modified by stacking alternate depositions of TaN and Si. The effective workfunction of the gate electrode can be adjusted through the average composition of the TaSixNy. Excellent transistor characteristics have been confirmed, using HfSiON gate dielectric and a TaSixNy gate electrode.