UV Absorption of KDP Single Crystals as a function of Growth Conditions

1993 ◽  
Vol 329 ◽  
Author(s):  
M. I. Kolybayeva ◽  
I. M. Pritula ◽  
V. I. Salo
Keyword(s):  
Growth Rate ◽  
Absorption Coefficient ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Crystallization Temperature ◽  
Growth Parameters ◽  
Uv Spectroscopy ◽  
Growth Conditions ◽  
Uv Absorption ◽  
Spectroscopy Method

AbstractUV-spectroscopy method is used to study the influence ofdifferent varying growth parameters (growth rate, crystallization temperature, pH of the solution, complexating additions) on the absorption spectra of KH2PO4 crystals. It is found that the minimal value of the absorption coefficient (k ˜ 0.01–0.02cm−1)may be achieved under the following growth conditions: 1) crystallization temperature ˜ 55°C, 2) growth rate ˜ 1mm/24hrs, 3)pH = 4.

Performance of a-Si-H Solar Cells at Higher Growth Rates

1999 ◽  
Vol 557 ◽  
Author(s):  
G. Ganguly ◽  
G. Lin ◽  
L.F. Chen ◽  
M. He ◽  
G. Wood ◽  
...  
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Growth Rates ◽  
Growth Parameters ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Growth Conditions ◽  
Plasma Decomposition ◽  
Hydrogen Mixtures ◽  
External Growth

AbstractWe have studied the effects of external growth parameters during the deposition of the i-layers of a-Si p-i-n solar cells using dc plasma decomposition of silane-hydrogen mixtures at growth rates of up to 3A/s. The loss of initial performance with increasing growth rate is mainly due to a loss of short-circuit current. The relative degradation of efficiency upon extended light soaking also increases with growth rate, and is mainly due to a decrease in the fill factor. Systematic comparisons of the performance and its degradation with changes in growth conditions reveal that these two components of the total degradation have distinct origins.

Aluminium Doping of 4H-SiC Grown with HexaMethylDiSilane

2005 ◽  
Vol 483-485 ◽  
pp. 121-124 ◽  
Author(s):  
C. Sartel ◽  
Véronique Soulière ◽  
Marcin Zielinski ◽  
Yves Monteil ◽  
Jean Camassel ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
P Systems ◽  
P System ◽  
Aluminium Concentration ◽  
P Type ◽  
Non Destructive ◽  
Aluminium Doping

We report on the study of the p-type doping of 4H-SiC material using HexaMethylDiSilane/TriMethylAluminium/Propane (HMDS/TMA/P) system in place of the usual Silane/TriMethylAluminium/Propane (S/TMA/P) precursors. The influence of growth parameters such as TMA flow, growth rate or C/Si ratio is investigated. The aluminium incorporation level is deduced from both by C(V) (mercury probe) and SIMS measurements. The presence of aluminium in the layers is confirmed by non-destructive optical micro-Raman experiments. Good quality p-type, aluminium doped 4H-SiC layers can be grown using HMDS/TMA/P system. The amount of aluminium in the layers can be controlled by choosing the growth conditions and an aluminium concentration as high as 2x1019 at.cm-3 has been reached.Finally, comparing the two HMDS/TMA/P and S/TMA/P systems, no difference in aluminium incorporation has been found.

Selective Area Heteroepitaxy of Nano-AlGaN UV Excitation Sources for Biofluorescence Application

2006 ◽  
Vol 916 ◽  
Author(s):  
Vibhu Jindal ◽  
James Grandusky ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
Joleyn Balch ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Selective Area ◽  
Mask Material ◽  
Uv Excitation ◽  
Selection Of

AbstractWe report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters; including temperature, pressure, NH3 flow, total alkyl flow and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant which resulted in a high quality pyramidal structure. As indicated by high resolution x-ray diffraction (XRD) and cathodoluminescence (CL) spectroscopy, composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Selective area heteroepitaxy of nano-AlGaN ultraviolet excitation sources for biofluorescence application

2007 ◽  
Vol 22 (4) ◽  
pp. 838-844 ◽  
Author(s):  
Vibhu Jindal ◽  
James R. Grandusky ◽  
Neeraj Tripathi ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultraviolet Excitation ◽  
Selective Area ◽  
Cathodoluminescence Spectroscopy ◽  
Mask Material ◽  
Selection Of

We report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters including temperature, pressure, NH3 flow, total alkyl flow, and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant, which resulted in a high-quality pyramidal structure. As indicated by high-resolution x-ray diffraction and cathodoluminescence spectroscopy, the composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Favourable growth conditions for the preparation of bulk AlN single crystals by PVT

CrystEngComm ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1762-1768 ◽  
Author(s):  
C. Hartmann ◽  
L. Matiwe ◽  
J. Wollweber ◽  
I. Gamov ◽  
K. Irmscher ◽  
...  
Keyword(s):  
Growth Rate ◽  
Single Crystals ◽  
Growth Conditions ◽  
Structural Perfection ◽  
High Structural Perfection ◽  
Deep Uv

A high seed temperature (2251 °C) reveals the highest deep UV transparency (α265nm = 27 cm−1), a high structural perfection (EPD = 9 × 103 cm−2) and a suitable growth rate (R = 200 μm h−1).

Directed exospermia: II. VUV-UV spectroscopy of specialized UV screens, including plant flavonoids, suggests using metabolic engineering to improve survival in space

2007 ◽  
Vol 6 (4) ◽  
pp. 291-301 ◽  
Author(s):  
Andreja Zalar ◽  
David Tepfer ◽  
Søren V. Hoffmann ◽  
Albert Kollmann ◽  
Sydney Leach
Keyword(s):  
Metabolic Engineering ◽  
Absorption Spectra ◽  
Dipicolinic Acid ◽  
Uv Spectroscopy ◽  
Uv Absorption ◽  
Uv Resistance ◽  
Uv Absorption Spectra ◽  
Plant Seeds ◽  
Solar Uv ◽  
Synchrotron Light

AbstractWe used synchrotron light to determine VUV-UV absorption spectra (125–340 nm) of thin films of substances associated with UV resistance in specific groups of organisms or across limited phylogenetic boundaries: scytonemin, mycosporine-like amino acids, dipicolinic acid, β-carotene, melanin and flavonoids (quercitrin, isoquercitrin, robinin and catechin). The objective was to extend known UV absorption spectra into the vacuum UV, and to evaluate the likely effectiveness of these molecules in shielding DNA from the unfiltered solar UV found in space, using similarity with DNA absorption spectra as the primary criterion. The spectroscopy indicated that plant flavonoids would be ideal UV screens in space. We suggest that flavonoids represent primitive UV screens, and offer explanations (including horizontal gene transfer) for their presence in plants. We also discuss the possibility of improving UV resistance by increasing flavonoid accumulation through metabolic engineering, in the hope of better adapting life for space travel, i.e. for its dissemination away from the Earth (exospermia). Finally, we propose using plant seeds as exospermia vehicles for sending life (including artificial life) into space.

The Effect of Growth Conditions on Carrier Lifetime in N-Type 4H-SiC Epitaxial Layers

2012 ◽  
Vol 717-720 ◽  
pp. 161-164 ◽  
Author(s):  
Louise Lilja ◽  
Jawad ul Hassan ◽  
I.D. Booker ◽  
Peder Bergman ◽  
Erik Janzén
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Epitaxial Growth ◽  
Carrier Lifetime ◽  
Growth Parameters ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Afm Analysis

Carrier lifetime has been studied as a function of C/Si ratio and growth rate during epitaxial growth of n-type 4H-SiC using horizontal hot-wall CVD. Effort has been put on keeping all growth parameters constant with the exception of the parameter that is intended to vary. The carrier lifetime is found to decrease with increasing growth rate and the highest carrier lifetime is found for a C/Si ratio of 1. The surface roughness was correlated with epitaxial growth conditions with AFM analysis.

Study of MBE ZnSe Growth Using Rheed Oscillations

1989 ◽  
Vol 145 ◽  
Author(s):  
Francoise S. Turco ◽  
M.C. Tamargo
Keyword(s):  
Growth Rate ◽  
Quantitative Study ◽  
Growth Parameters ◽  
Growth Conditions ◽  
High Energy ◽  
Growth Mechanisms ◽  
Mbe Growth ◽  
Wide Range ◽  
Main Growth

AbstractReflection high energy electron diffraction (RHEED) intensity oscillations are often used to investigate in situ the growth of III-V materials by molecular beam epitaxy (MBE). In this work, we have used RHEED oscillations to perform a quantitative study of the growth mechanisms of ZnSe, a II-VI semiconductor.Our experiments illustrate that the RHEED pattern of ZnSe is far less intense than that of III-V materials grown by MBE, and no specular spot is observed over a wide range of growth conditions. We have, however, been able to record up to 25 oscillations allowing a quantitative study of the growth of ZnSe by MBE. Thus we have used RHEED oscillations to make an in situ systematic study of the influence of the three main growth parameters (substrate temperature and Zn or Se impinging fluxes) on the ZnSe growth rate. We observed that the variation of the ZnSe growth rate is due to a non unity sticking coefficient of both Zn and Se species at the interface in the standard growth conditions used. Our observations can be described using a thermodynamic model and enable us to control the desired growth conditions. Our work demonstrates the utility of RHEED oscillations to understand the MBE growth mechanisms of II-VI compounds.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

Sign in / Sign up

Export Citation Format

Share Document