The Farthest Reaches of a-Si,Ge:H,F Parameter Space… Where no One Has Gone Before

1992 ◽  
Vol 258 ◽  
Author(s):  
P.A. Morin ◽  
N.W. Wang ◽  
S. Wagner
Keyword(s):  
Growth Rate ◽  
Parameter Space ◽  
Growth Rates ◽  
Film Growth ◽  
Defect Density ◽  
Initial Defect ◽  
Figures Of Merit ◽  
Rate Dependent ◽  
Deposition Parameters ◽  
Defect Densities

ABSTRACTWe report the deposition parameters for optimized a-Si,Ge:H,F alloys in the range of optical (Taue) gap of 1.22eV to 1.65eV. These deposition parameters were optimized using the photosensitivity and initial defect density as figures of merit. We observe two distinct regimes of film growth rate, dependent on the choice of source gases. Growth from fluoride source gases results in a growth rate of less than 0.6 Ås--1. Growth from a mixture of fluorides and silane gives a range of growth rates from 2 Ås-l to 5.5Ås1. Alloys in both regimes display the low defect densities and the high photosensitivities required for devices.

Optimization of the Deposition Conditions for High-Gap a-Si,Ge:H,F Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
P.A. Morin ◽  
N.W. Wang ◽  
S. Wagner
Keyword(s):  
Figure Of Merit ◽  
Defect Density ◽  
Initial Defect ◽  
Optical Gap ◽  
Deposition Parameters ◽  
Defect Densities ◽  
Deposition Conditions

ABSTRACTWe report the deposition parameters for optimized a-Si,Ge:H,F alloys in the range of optical (Taue) gap 1.5 leV to 1.62eV. These deposition parameters were optimized using the saturated defect density as a figure of merit. We report initial defect densities at or below 2.5×1016 cm-3, saturated defect densities below 9×1016 cm-3, photoconductivities (at G = 1021 cm-3s-1) between 8.7×10-6 Scm-1 and 7×10-5 Scm-land photosensitivities between 104 and 105 for alloys in this range of optical gap.

Control of Materials and Interfaces in μc-Si:H-based Solar Cells Grown at High Rate

2011 ◽  
Vol 1321 ◽  
Author(s):  
Yasushi Sobajima ◽  
Chitose Sada ◽  
Akihisa Matsuda ◽  
Hiroaki Okamoto
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Film Growth ◽  
Defect Density ◽  
Density Measurement ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Bulk Region ◽  
Dangling Bond

ABSTRACTGrowth process of microcrystalline silicon (μc-Si:H) using plasma-enhanced chemicalvapor- deposition method under high-rate-growth condition has been studied for the control of optoelectronic properties in the resulting materials. We have found two important things for the spatial-defect distribution in the resulting μc-Si:H through a precise dangling-bond-density measurement, e. g., (1) dangling-bond defects are uniformly distributed in the bulk region of μc- Si:H films independent of their crystallite size and (2) large number of dangling bonds are located at the surface of μc-Si:H especially when the film is deposited at high growth rate. Starting procedure of film growth has been investigated as an important process to control the dangling-bond-defect density in the bulk region of resulting μc-Si:H through the change in the electron temperature by the presence of particulates produced at the starting period of the plasma. Deposition of Si-compress thin layer on μc-Si:H grown at high rate followed by thermal annealing has been proposed as an effective method to reduce the defect density at the surface of resulting μc-Si:H. Utilizing the starting-procedure-controlling method and the compress-layerdeposition method together with several interface-controlling methods, we have demonstrated the fabrication of high conversion-efficiency (9.27%) substrate-type (n-i-p) μc-Si:H solar cells whose intrinsic μc-Si:H layer is deposited at high growth rate of 2.3 nm/sec.

scholarly journals Growth Rate-Dependent Accumulation of RNA from Plasmid-Borne rRNA Operons in Escherichia coli

1998 ◽  
Vol 180 (7) ◽  
pp. 1970-1972 ◽  
Author(s):  
Bradley S. Stevenson ◽  
Thomas M. Schmidt
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Doubling Time ◽  
Slow Growth ◽  
Metabolic Burden ◽  
Rate Dependent ◽  
Rna Concentration

ABSTRACT Inadequate regulation of the expression of additional plasmid-borne rRNA operons in Escherichia coli was exaggerated at slow growth rates, resulting in increases of approximately 100% for RNA concentration and 33% for doubling time. These observations are consistent with the hypothesis that multiple rRNA operons constitute a metabolic burden at slow growth rates.

The Effect of Phosphine Pressure on the Band Gap of Ga0.5In0.5P

1994 ◽  
Vol 340 ◽  
Author(s):  
Sarah R. Kurtz ◽  
D. J. Arent ◽  
K. A. Bertness ◽  
J. M. Olson
Keyword(s):  
Growth Rate ◽  
Surface Structure ◽  
Band Gap ◽  
Surface Diffusion ◽  
Parameter Space ◽  
Growth Temperature ◽  
Growth Rates ◽  
Diffusion Length ◽  
Group V ◽  
Group Iii

ABSTRACTThe band gap of Ga0.51n0.5P is studied as a function of phosphine pressure, B-type substrate misorientation, growth rate, and growth temperature, with emphasis placed on the effect of the phosphine pressure. Over most of the parameter space explored (high temperatures, large substrate misorientations, and low growth rates), the band gap increases with decreasing phosphine. This increase is proposed to be caused by lower phosphorus coverage of the surface, resulting in a different surface structure that doesn't promote ordering. The implications of this effect on the observed variations of band gap with growth temperature, substrate misorientation, and growth rate are discussed. For regions of parameter space in which the ordering appears to be kinetically limited by surface diffusion, the band gap increases slightly with phosphine pressure, consistent with observations that increased group-V pressure decreases the group-III surface diffusion length.

Thin YSZ Electrolyte Film Depositions on Dense and Porous Substrates

Materials ◽  
2003 ◽  
Author(s):  
Zhigang Xu ◽  
Corydon Hilton ◽  
Bobby Watkins ◽  
Sergey Yarmolenko ◽  
Jag Sankar
Keyword(s):  
Growth Rate ◽  
Film Growth ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Lanthanum Manganite ◽  
Deposition Parameters ◽  
Pore Sealing ◽  
Complex Deposition ◽  
Initial Deposition ◽  
Ysz Electrolyte

Yttria stabilized zirconia (YSZ) thin films have been processed on polished silicon and porous strontium-doped lanthanum manganite (LSM) substrates by liquid fuel combustion chemical vapor deposition from combustion of an aerosol jet. The aerosol jet consists of Y- and Zr- containing metalorganics dissolved in toluene and high-purity oxygen. The morphology and thickness of the deposited films have been analyzed with scanning electron microscope. On the polished silicon substrates, thin and uniform films have been obtained. The grain growth rate is of the first order of the deposition time. The film growth rate was greatly enhanced by utilizing higher precursor concentrations, proper substrate temperature and the effect of thermophoresis. However, when the porous substrate is being coated, a more complex deposition process takes place. The initial deposition seems to be favored on the surface protrusions. Therefore, the covered areas serve as nucleation sites and the grains start to grow, giving rise to larger particles and rougher surface than the films on polished silicon. To enhance the pore-sealing rate, some pre-treatments and post-treatment have been used. Moreover, deposition parameters towards fast pore sealing have been investigated. Thin and continuous films with the film thickness less than 3 μm have been obtained.

scholarly journals Growth Rate-Dependent Control in Enterococcus faecalis: Effects on the Transcriptome and Proteome, and Strong Regulation of Lactate Dehydrogenase

2011 ◽  
Vol 78 (1) ◽  
pp. 170-176 ◽  
Author(s):  
Ibrahim Mehmeti ◽  
Ellen M. Faergestad ◽  
Martijn Bekker ◽  
Lars Snipen ◽  
Ingolf F. Nes ◽  
...  
Keyword(s):  
Growth Rate ◽  
Lactate Dehydrogenase ◽  
Enterococcus Faecalis ◽  
Growth Rates ◽  
Posttranscriptional Regulation ◽  
High Growth ◽  
Regulation Of Expression ◽  
Lower Growth ◽  
Content Type ◽  
Rate Dependent

ABSTRACTEnterococcus faecalisV583 was grown in a glucose-limited chemostat at three different growth rates (0.05, 0.15, and 0.4 h−1). The fermentation pattern changed with growth rate, from a mostly homolactic profile at a high growth rate to a fermentation dominated by formate, acetate, and ethanol production at a low growth rate. A number of amino acids were consumed at the lower growth rates but not by fast-growing cells. The change in metabolic profile was caused mainly by decreased flux through lactate dehydrogenase. The transcription ofldh-1, encoding the principal lactate dehydrogenase, showed very strong growth rate dependence and differed by three orders of magnitude between the highest and the lowest growth rates. Despite the increase inldh-1 transcript, the content of the Ldh-1 protein was the same under all conditions. Using microarrays and quantitative PCR, the levels of 227 gene transcripts were found to be affected by the growth rate, and 56 differentially expressed proteins were found by proteomic analyses. Few genes or proteins showed a growth rate-dependent increase or decrease in expression across the whole range of conditions, and many showed a maximum or minimum at the middle growth rate (i.e., 0.15 h−1). For many gene products, a discrepancy between transcriptomic and proteomic data were seen, indicating posttranscriptional regulation of expression.

Effect Of Increasing Growth Rates on Film Properties and Device Performance for DC Glow Discharge Amorphous Silicon

2002 ◽  
Vol 715 ◽  
Author(s):  
Jennifer T. Heath ◽  
James J. Gutierrez ◽  
J. David Cohen ◽  
Gautam Ganguly
Keyword(s):  
Growth Rate ◽  
Amorphous Silicon ◽  
Film Growth ◽  
Drive Level ◽  
Device Performance ◽  
Dc Glow Discharge ◽  
Film Properties ◽  
Defect Band ◽  
Device Efficiency ◽  
Defect Densities

AbstractWe have examined the electronic properties of intrinsic amorphous silicon films as a function of deposition rate, and compared these with the performance of companion solar cell p-i-n devices. The device efficiency in the light-soaked state was strongly inversely correlated with growth rate. Film properties were evaluated in both the as-grown and light soaked states using drive-level capacitance profiling and transient photocapacitance spectroscopy. Although deep defect densities measured by drive-level capacitance profiling did not vary significantly between samples, the magnitude of the defect band deduced via transient photocapacitance spectroscopy was well correlated with device performance. Possible reasons for this discrepancy are discussed. Urbach energies were also correlated with film growth rate.

Fast 4H-SiC Epitaxial Growth on 150 mm Diameter Area with High-Speed Wafer Rotation

2014 ◽  
Vol 778-780 ◽  
pp. 117-120 ◽  
Author(s):  
Hiroaki Fujibayashi ◽  
Masahiko Ito ◽  
Hideki Ito ◽  
Isaho Kamata ◽  
Masami Naitou ◽  
...  
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Growth Rates ◽  
High Speed ◽  
Smooth Surface ◽  
Doping Concentration ◽  
Defect Density ◽  
High Growth ◽  
High Growth Rate ◽  
Step Bunching

A single wafer type 150 mm vertical 4H-SiC epitaxial reactor with high-speed wafer rotation was developed. The rotation of the wafer at high speed significantly enhances the growth rate, and high growth rates of 40–50 μm/h are possible on 4°off-cut 4H-SiC substrates. In addition, a low defect density and smooth surface without macro step bunching can be achieved. Excellent uniformity of thickness and doping concentration was obtained for a 150 mm wafer at a high growth rate of 50 μm/h.

Hydrogen Injection in ETP Plasma Jet for Fast-Deposition of High-Quality a-Si:H

2004 ◽  
Vol 808 ◽  
Author(s):  
A.M.H.N. Petit ◽  
R.A.C.M.M. van Swaaij ◽  
M.C.M. van de Sanden
Keyword(s):  
Growth Rate ◽  
Hydrogen Content ◽  
Growth Rates ◽  
Plasma Chemistry ◽  
High Growth ◽  
Plasma Jet ◽  
Solar Cell Application ◽  
Microstructure Parameter ◽  
Strong Relation ◽  
Defect Densities

ABSTRACTWe have used a cascaded-arc expanding thermal plasma (ETP) to produce thin films of amorphous silicon at high growth rates (> 3 nm/s). Here, we present a study of the effect on material properties of hydrogen injection in the nozzle, i.e., at the exit of the arc where the plasma expands into the reactor chamber. The advantage of using extra H2 in the nozzle is that the plasma chemistry and pressure in the arc remain unchanged, whilst higher growth rates and a material with low defect densities can be obtained.We observe that with an increase of substrate temperature the growth rate decreases due to densification of the material. This densification is accompanied by a reduction of the hydrogen content and of the microstructure parameter. Further we observe that hydrogen content decreases with higher growth rate. A strong relation is found between the light conductivity and the microstructure parameter indicating a large void fraction in samples grown at low temperature.We have been able to grow a-Si:H material, with H2 in the nozzle, at 350°C and 3 nm/s with a light conductivity of 1.2 × 10−5 Ω1cm−1, which can be suitable for solar-cell application.

scholarly journals Stability of three-dimensional Gaussian vortices in an unbounded, rotating, vertically stratified, Boussinesq flow: linear analysis

2017 ◽  
Vol 824 ◽  
pp. 97-134 ◽  
Author(s):  
Mani Mahdinia ◽  
Pedram Hassanzadeh ◽  
Philip S. Marcus ◽  
Chung-Hsiang Jiang
Keyword(s):  
Growth Rate ◽  
Parameter Space ◽  
Accretion Disks ◽  
Growth Rates ◽  
Three Dimensional ◽  
Boussinesq Equations ◽  
Small Region ◽  
Giant Planets ◽  
Ocean Eddies ◽  
The Stability

The linear stability of three-dimensional vortices in rotating, stratified flows has been studied by analysing the non-hydrostatic inviscid Boussinesq equations. We have focused on a widely used model of geophysical and astrophysical vortices, which assumes an axisymmetric Gaussian structure for pressure anomalies in the horizontal and vertical directions. For a range of Rossby numbers ($-0.5<Ro<0.5$) and Burger numbers ($0.02<Bu<2.3$) relevant to observed long-lived vortices, the growth rate and spatial structure of the most unstable eigenmodes have been numerically calculated and presented as a function of $Ro{-}Bu$. We have found neutrally stable vortices only over a small region of the $Ro{-}Bu$ parameter space: cyclones with $Ro\sim 0.02{-}0.05$ and $Bu\sim 0.85{-}0.95$. However, we have also found that anticyclones in general have slower growth rates compared to cyclones. In particular, the growth rate of the most unstable eigenmode for anticyclones in a large region of the parameter space (e.g. $Ro<0$ and $0.5\lesssim Bu\lesssim 1.3$) is slower than 50 turnaround times of the vortex (which often corresponds to several years for ocean eddies). For cyclones, the region with such slow growth rates is confined to $0<Ro<0.1$ and $0.5\lesssim Bu\lesssim 1.3$. While most calculations have been done for $f/\bar{N}=0.1$ (where $f$ and $\bar{N}$ are the Coriolis and background Brunt–Väisälä frequencies), we have numerically verified and explained analytically, using non-dimensionalized equations, the insensitivity of the results to reducing $f/\bar{N}$ to the more ocean-relevant value of 0.01. The results of our stability analysis of Gaussian vortices both support and contradict the findings of earlier studies with QG or multilayer models or with other families of vortices. The results of this paper provide a stepping stone to study the more complicated problems of the stability of geophysical (e.g. those in the atmospheres of giant planets) and astrophysical vortices (in accretion disks).

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