Search results for " silicon"

Vacuum-ultraviolet absorption of amorphous SiO2: intrinsic disorder and role of silanol groups

2008

We present a study on the vacuum-ultraviolet VUV absorption properties of amorphous SiO2 a-SiO2 with high concentrations of silanol groups Si-OH . We found that the absorption spectra are made up of a couple of exponential profiles. The first, in the range from 7.5 to 8.1 eV, was attributed to Si-OH group absorption, while the second, in the range from 8.1 to 8.25 eV, was ascribed to the intrinsic absorption. The VUV absorption cross section of Si-OH groups in a-SiO2 was determined as well. The intrinsic absorption was found to be affected by the Si-OH concentration: high silanol group contents allow lower values of the Urbach energy. This result is interpreted in terms of a reduction in th…

Sturctural disorder and silanol groups content in amorphous SiO2

2009

We present a study on the features of the Urbach edge in amorphous silicon dioxide a-SiO2 . The effects of temperature on the absorption edge in the range from 4 to 300 K were studied in both materials having negligible dry, 1017 cm−3 and significant wet, 1019 cm−3 silanol groups contents. Remarkable differences in the values and in the temperature dependence of the Urbach energy in the dry and wet samples were observed. These differences are interpreted as a consequence of a drastic reduction in the degree of disorder in wet materials, which turn out to be characterized by an electronic structure more similar to that of crystalline quartz. Furthermore, our results indicate that silanol gro…

The Large Area Detector onboard the eXTP mission

2022

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, a…

Metal displacement deposition: a new method to grow amorphous silicon nanotubes

2013

A novel approach for parameters determination in four lumped PV parametric model with operative range evaluations

2013

The paper presents a novel numerical approach for the parameters determination of crystalline silicon PV models four lumped parameters equivalent circuit. The novel approach basically deals with a new method, alternative to the iterative one known in literature, to calculate the series resistance. Particularly, it allows the evaluation of the lumped parameters on the basis of the manufacturer’s datasheet. The new approach has been validated both in the Maximum Power Point (MPP) and close to it by comparing values and curves obtained by means of the model implementation in Matlab/Simulink environment with those related to some five parameters models and manufacturer curves. Results show that…

Telecom-compatible, affordable and scalable quantum technologies

2022

The realistic implementation of quantum architectures relies on the development of scalable, resource-efficient platforms that are compatible with CMOS technologies as well as fiber networks. This work demonstrates novel schemes utilized for time-/frequency-bin entanglement generation and processing by leveraging existing telecommunications and integrated photonics infrastructures.

Signal to Noise Ratio of Silicon Photomultipliers: a study in the Continuous Wave Regime

2014

We report on Signal to Noise Ratio measurements carried out, in the continuous wave regime, at different bias voltages, frequencies and temperatures, on a novel class of silicon photomultipliers fabricated in planar technology on silicon p-type substrate. Signal to Noise Ratio has been measured as the ratio of the photogenerated current, filtered and averaged by a lock-in amplifier, and the Root Mean Square deviation of the same current. The measured noise takes into account the shot noise, resulting from the photocurrent and the dark current. We have also performed a comparison between our SiPMs and a photomultiplier tube in terms of Signal to Noise Ratio, as a function of the temperature …

Resistance to disinfection of a polymicrobial association contaminating the surface of elastomeric dental impressions.

2009

The aim of this study was to evaluate the ability to resist disinfection of a polymicrobial association contaminating the surface of dental impressions obtained with two different elastomers: a polyether (Impregum) and an addition-polymerized silicone (Elite). Impressions were contaminated with a mixture of three biofilm-forming microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans) and disinfected immediately after contamination, or after microbial layers were allowed to develop during a six-hour storage. Two commercial disinfectants were tested: MD 520 containing 0.5% glutaraldehyde and Sterigum Powder without glutaraldehyde. Residual contamination was recover…

Measurements of Silicon Photomultipliers Responsivity in Continuous Wave

2012

N-on-P and P-on-N Silicon Photomultipliers: Responsivity comparison in the continuous wave regime

2013

We report on the electrical and optical comparison, in continuous wave regime, of two novel classes of silicon photomultipliers fabricated in planar technology on silicon P-type and Ntype substrate respectively. A physical explanation of the experimental results is provided.