Search results for "silicon"

Minimum detection limits and applications of proton and helium induced X-ray emission using transition-edge sensor array

2017

Abstract We have determined minimum detection limits, MDLs, for elements 14 ⩽ Z ⩽ 86 using a transition-edge sensor array, TES array, and as a comparison using an Amptek X-123SDD silicon drift detector, SDD. This was done using a 3 MeV proton beam and a 5.1 MeV helium beam. MDLs were determined for a thin film sample on top of C substrate, and for a bulk sample containing mostly Al. Due to the higher peak-to-background ratio, lower detection limits were obtainable using the TES array for most of the elements. However, for elements 30 ⩽ Z ⩽ 45 the performance of the TES array was not as good as the SDD performance. This is due to the limitations of the TES used at energies >10 keV. The great…

The Silicon Photomultiplier: a promising photodetector for biosensing applications

Anomalous performance enhancement effects in Ruthenium-based Dye Sensitized Solar Cells

2017

Dye Sensitized Solar Cells (DSSCs) are nowadays more and more employed since they present lower production costs than traditional silicon photovoltaic devices. An interesting phenomenon affecting such devices consists in the fact that current density-voltage (J-V) characteristic can depend on the history of the cell prior to the measurement, which often can be assimilated to an anomalous hysteresis effect. In this work, we study such phenomenon on Ruthenium-based DSSCs through a series of measurements performed after applying different values of external electrical field to the cell. The measurements have been carried out both under simulated sunlight (AM1.5G - 1000 W/m2) and in the dark. W…

Design and performance of the prototype Schwarzschild-Couder telescope camera

2022

Journal of astronomical telescopes, instruments, and systems 8(01), 014007-1 (2022). doi:10.1117/1.JATIS.8.1.014007

Cathodoluminescence and photoluminescence study of trap centers in amorphous silicon oxynitride

2002

Amorphous silicon oxynitride (a-SiO/sub x/N/sub y/) films with different compositions were prepared using low-pressure chemical vapor deposition (LPCVD) technique, The cathodoluminescence and photoluminescence of this samples were measured from the red band to the ultraviolet band to study the trap centers in silicon oxynitride. A 1.8-1.9 eV band was found and is attributed to the oxygen and nitrogen atoms with unpaired electrons whereas the 2.7 eV band is attributed to two-fold coordinated silicon atoms with two electrons. The 5.4 eV shoulder is due to the peroxy radicals and other ultraviolet bands are supposed to due due to the Si-Si bonds.

Anomalous and normal Hall effect in hydrogenated amorphous Si prepared by plasma enhanced chemical vapor deposition

2010

The double sign anomaly of the Hall coefficient has been studied in p -doped and n -doped hydrogenated amorphous silicon grown by plasma enhanced chemical vapor deposition and annealed up to 500 °C. Dark conductivity as a function of temperature has been measured, pointing out a conduction mechanism mostly through the extended states. Anomalous Hall effect has been observed only in the as-deposited n -doped film, disappearing after annealing at 500 °C, while p -doped samples exhibit normal Hall effect. When Hall anomaly is present, a larger optical band gap and a greater Raman peak associated with Si-H bond are measured in comparison with the cases of normal Hall effect. The Hall anomaly wi…

Enhanced Heterogeneous Catalytic Conversion of Furfuryl Alcohol into Butyl Levulinate

2014

We study the catalytic condensation of furfuryl alcohol with 1-butanol to butyl levulinate. A screening of several commercial and as-synthesized solid acid catalysts shows that propylsulfonic acid-functionalized mesoporous silica outperforms the state-of-the-art phosphotungstate acid catalysts. The catalyst is prepared via template-assisted sol-gel polycondensation of TEOS and MPTMS. It gives 96 % yield (and 100 % selectivity) of butyl levulinate in 4h at 110 °C. Reaction profiles before and after a hot filtration test confirm that the active catalytic species do not leach into the solution. The catalyst synthesis, characterization, and mode of operation are presented and discussed. Sour ca…

Comparative study of initial stages of copper immersion deposition on bulk and porous silicon

2013

Initial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, dens…

Calcium silicate hydrates: Solid and liquid phase composition

2015

© 2015 Elsevier Ltd. This paper presents a review on the relationship between the composition the structure and the solution in which calcium silicate hydrate (C S H) is equilibrated. The silica chain length in C S H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space preferentially at low calcium concentrations and thus by low Ca/Si C S H. Aluminium uptake in C S H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si aluminium substitutes silica in the bridging position at Ca/Si. > 1 aluminium is bound in TAH. Recently developed ther…

Accelerated Light-Induced Defect Transformation Study of Elkem Solar Grade Silicon

2012

AbstractSolar cells made of silicon feedstock from a metallurgical route must qualify not only the initial efficiency, but must also be comparable to the solar cells made from reference polysilicon on the spectral response after light induced degradation. A detailed comparative study of light induced defects and its impact on cell performance is necessary for both materials. We have studied accelerated light induced degradation (ALID) defect transformation for Elkem Solar Silicon and polysilicon solar cells by selecting wafers from different positions from respective silicon bricks. Active boron-oxygen complexes and iron ions in multicrystalline silicon solar cells have been analyzed, and t…