Search results for " SOLID"

Molecular dynamics simulation of epitaxial growth of the Si(001) surface

1988

Abstract Molecular beam epitaxy on a Si(100) substrate has been studied using a molecular dynamics method with the Stillinger-Weber model potential. At high substrate temperature, 800 K, well ordered crystalline layers are found to grow underneath an amorphous overlayer of approximately 5 A thick. A limiting temperature for epitaxial growth is found to be 480 K, below which the growth does not produce ordered layers. When the sample deposited below 480 K is heated up to 800 K and the deposition is started again the original adatoms start to form ordered atomic layers. Thus the collisions of the deposited atoms in addition to the substrate temperature seem to play an essential role in the gr…

Role of the strain in the epitaxial regrowth rate of heavily doped amorphous Si films

2008

Solid phase epitaxial regrowth (SPER) of p -doped preamorphized Si was studied by time resolved reflectivity. Strain and dopant concentration were opportunely varied by implanting neutral (Ge) and isovalent (B, Ga) impurities in order to disentangle the two different effects on SPER. Larger SPER rate variations occurred in strained doped Si with respect to undoped samples. The generalized Fermi level shifting model was implemented to include the role of the strain and to fit the experimental data over a large range of temperature for p - and n -type doping. We introduced a charged defect, whose energy level is independent of the dopant species. © 2008 American Institute of Physics.

Energy balance in single exposure multispectral sensors

2013

International audience; Recent simulations of multispectral sensors are based on a simple Gaussian model, which includes filters transmittance and substrate absorption. In this paper we want to make the distinction between these two layers. We discuss the balance of energy by channel in multispectral solid state sensors and propose an updated simple Gaussian model to simulate multispectral sensors. Results are based on simulation of typical sensor configurations.

Cathodoluminescence decay kinetics in Ge+, Si+, O+ implanted SiO2 layers

2003

Abstract Cathodoluminescence spectral shapes and respective band decay times show no similarity between luminescence centers in different crystal and amorphous modifications of SiO2 and GeO2. On the other hand, the additionally produced red luminescence centers (650 nm) by oxygen implantation into SiO2 layers are of the same nature as in stoichiometric SiO2 and are attributed to the non-bridging oxygen hole center (NBOHC). On the other hand, the elevated blue luminescence (460 nm) in Si implanted SiO2 belongs to the silicon related oxygen deficient center (SiODC) as in stoichiometric layers also. Ge implantation into SiO2 and thermal post-annealing leads to a huge violet luminescence (400 n…

Bimodal Acidity at the Amorphous Silica/Water Interface

2015

International audience; Understanding the microscopic origin of the acid base behavior of mineral surfaces in contact with water is still a challenging task, for both the experimental and the theoretical communities. Even for a relatively simple material, such as silica, the origin of the bimodal acidity behavior is still a debated topic. In this contribution we calculate the acidity of single sites on the humid silica surface represented by a model for the hydroxylated amorphous surface. Using a thermodynamic integration approach based on ab initio molecular dynamics, we identify two different acidity values. In particular, some convex geminals and some type of vicinals are very acidic (pK…

Effect of surface treatment with sandblasting and Er,Cr:YSGG laser on bonding of stainless steel orthodontic brackets to silver amalgam

2011

Objectives: Satisfactory bonding of orthodontic attachments to amalgam is a challenge for orthodontists. The aim of this in vitro study was to compare the shear bond strength of stainless steel orthodontic brackets to silver amalgam treated with sandblasting and Er,Cr:YSGG laser. Study Design: Fifty-four amalgam discs were prepared, polished and divided into three groups: In group 1 (the control group) the premolar brackets were bonded using Panavia F resin cement without any surface treatment; in groups 2 and 3, the specimens were subjected to sandblasting and Er,Cr:YSGG laser respectively, before bracket bonding. After immersing in distilled water at 37°C for 24 hours, all the specimens w…

Re: Small solid renal masses: Characterization by diffusion-weighted MRI at 3 T. A reply.

2014

No abstract available.

La gangrena

2003

Una ciudadanía alternativa

2003

Sociālais darbinieks kā starppaaudžu solidaritātes veicinātājs kultūras programmu organizēšanā

2020

Pētījuma tēma ir “Sociālais darbinieks kā starppaaudžu solidaritātes veicinātājs kultūras programmu organizēšanā”. Pētījuma mērķis ir iztirzāt sociālā darbinieka dalību starppaaudžu solidaritātes veicināšanā, organizējot kultūras pasākumus ilgstošas sociālās aprūpes un sociālās rehabilitācijas institūcijās. Pētījuma teorētiskā bāze balstās uz lomu teoriju un ekosistēmisko teoriju sociālā darba kontekstā, kā arī uz starppaaudžu solidaritātes skaidrojumu, izmantojot sešu elementu starppaaudžu solidaritātes modeli. Pētījums ir kvalitatīvs gadījuma pētījums, kurā kā datu vākšanas metodes izmantotas daļēji strukturētas intervijas un ekspressintervijas. Pētījuma empīriskajā daļā tiek veikta inter…