Search results for "Germanium"
showing 10 items of 249 documents
High-Resolution Spectroscopy and Analysis of the ν3 and ν4 Fundamentals of Monoisotopic 70GeF4
2001
The first high-resolution study on germanium tetrafluoride is reported. We used a monoisotopic sample of (70)GeF(4). The FTIR spectra of the two infrared active fundamentals, namely the nu(4) (bending) and nu(3) (stretching) modes, were recorded at a temperature of ca. 210 K and a resolution (1/maximum optical path difference) of 0.0031 and 0.0023 cm(-1), respectively. These spectra were analyzed using the STDS software developed in Dijon. In both cases, we obtained a fit with a root mean square better than 1x10(-3) cm(-1). Both bands show very regular structures with no detectable perturbation. Copyright 2001 Academic Press.
Ge-doped silica nanoparticles: production and characterisation
2016
Silica nanoparticles were produced from germanosilicate glasses by KrF laser irradiation. The samples were investigated by cathodoluminescence and scanning electron microscopy, providing the presence of nanoparticles with size from tens up to hundreds of nanometers. The emission of the Germanium lone pair center is preserved in the nanoparticles and atomic force microscopy revealed the presence of no spherical particles with a size smaller than ~4 nm. The absorption coefficient enhancement induced by Ge doping is reputed fundamental to facilitate the nanoparticles production. This procedure can be applied to other co-doped silica materials to tune the nanoparticles features.
Germanium microparticles as optically induced oscillators in optical tweezers
2019
Oscillatory dynamics is a key tool in optical tweezers applications. It is usually implemented by mechanical interventions that cannot be optically controlled. In this work we show that Germanium semiconductor beads behave as optically induced oscillators when subjected to a highly focused laser beam. Such unusual motion is due to the competition between the usual optical forces [1-3] and the radiometric force related to thermal effects, which pushes the beads from the focal region [4]. We characterize the behavior of the Germanium beads in detail and propose a model accounting for the related forces, in good agreement with the experimental data. The well defined direction of oscillations c…
Preparation and structural study of sodium germanium phosphate-sodium titanium phosphate solid solutions. I. Evolution of structure with composition
1993
Compounds NaM2IV(PO4)3 with M = Ge, Ti present the [NZP]-type structure, with a low thermal expansion. The space group at room temperature for the compound NaGe2(PO4)3 is R3, whereas for the compound NaTi2(PO4)3 is R3c. Evolution of the structure with composition in NaGe2(PO4)3 NaTi2(PO4)3 system is discussed. The space group and lattice parameters were determined for NaGe2−xTix(PO4)3 (0 < x < 2) solid solutions, prepared by ceramic method. Compositions rich in Ge(IV) (0 ≤ x ≤ 1) show the R3 space group, whereas for those rich in Ti(IV) (1.2 ≤ x ≤ 2) the space group is R3c. The variation of the lattice parameters with composition agreed with these results since it showed a change in its t…
<title>Metallic and semiconducting nanowires: properties and architectures</title>
2003
Nanowires are expected to play an important role in future electronic, optical devices and nanoelectromechanical devices. Measuring the electrical and mechanical properties of nanowires is however a difficult task due to their small dimensions. Here we report the use of an in-situ microscopy technique, which combines transmission electron microscopy (TEM) with scanning probe microscopy (SPM), to investigate the electrical and mechanical properties of metallic and semiconductor nanowires. Additionally, in this paper we describe a novel approach for synthesizing mesoporous silicas with tunable pore diameters, wall thickness and pore spacings that can be used as tempates for the assembly of se…
Luminescence of unfused 95%SiO2–5%GeO2 amorphous films with fluorine additive: No evidence for presence of GeODC(I) defects found
2013
Abstract Photoluminescence (PL) of unfused amorphous germanosilicate films with fluorine additive is studied in 2–8.5 eV spectral range. Experiments are based on films deposited on silica substrates by means of the surface-plasma chemical vapor deposition (SPCVD). Films of about 100 μm in thickness with “high F” (~ 4.2 wt.%) and “low F” (~ 0.5 wt.%) fluorine content have been fabricated for the experiments. KrF (248 nm), ArF (193 nm) and F2 (157 nm) excimer lasers are used to pump PL. It is found that absorption and luminescence associated with germanium oxygen deficient centers (GeODCs) in “high F” and “low F” films differ. In the “high F” unfused film absorption coefficient of the band at…
Transient photoresponse and incident power dependence of high-efficiency germanium quantum dot photodetectors
2012
We report a systematic study of time-resolved and power-dependent photoresponse in high-efficiency germanium quantum dot photodetectors (Ge-QD PDs), with internal quantum efficiencies greater than 100 over a broad wavelength, reverse bias, and incident power range. Turn-on and turn-off response times (τ on and τ off) are shown to depend on series resistance, bias, optical power, and thickness (W QD) of the Ge-QD layer, with measured τ off values down to ∼40 ns. Two different photoconduction regimes are observed at low and high reverse bias, with a transition around -3 V. A transient current overshoot phenomenon is also observed, which depends on bias and illumination power. © 2012 American …
The “accumulation effect” of positrons in the stack of foils, detected by measurements of the positron implantation profile
2013
The profiles of positrons implanted from the radioactive source 22Na into a stack of foils and plates are the subject of our experimental and theoretical studies. The measurements were performed using the depth scanning of positron implantation profile method, and the theoretical calculations using the phenomenological multi-scattering model (MSM). Several stacks consisting of silver, gold and aluminum foils, and titanium and germanium plates were investigated. We notice that the MSM describes well the experimental profiles; however when the stack consisting of silver and gold foils, the backscattering and linear absorption coefficients differ significantly from those reported in the litera…
Luminescence of phosphorus doped silica glass
2017
This work is supported by Material Science program IMIS2 of Latvia.
Growth kinetics of colloidal Ge nanocrystals for light harvesters
2016
Colloidal Ge nanocrystals (NCs) are gaining increased interest because of their potential application in low-cost optoelectronic and light harvesting devices. However, reliable control of colloidal NC synthesis is often an issue and a deeper understanding of the key-role parameters governing NC growth is highly required. Here we report an extended investigation on the growth of colloidal Ge NCs synthesized from a one-pot solution based approach. A systematic study of the effects of synthesis time, temperature and precursor concentration is elucidated in detail. X-ray diffraction (XRD) analysis reveals the presence of crystalline Ge NCs with a mean size (from 5 to 35 nm) decreasing with the …