Correlation between Powder in the Plasma and Stability of High Rate Deposited a-Si:H

2005 ◽  
Vol 862 ◽  
Author(s):  
Guozhen Yue ◽  
Gautam Ganguly ◽  
Baojie Yan ◽  
Jeffrey Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Light Intensity ◽  
Scattered Light ◽  
Scattered Light Intensity ◽  
High Rate ◽  
Invasive Technique ◽  
High Deposition Rate ◽  
Very High Frequency ◽  
Silicon Photodiode ◽  
Non Invasive

AbstractHydrogenated amorphous silicon (a-Si:H) solar cells incorporating high deposition rate (8-10Å/s) intrinsic layers were deposited using modified very high frequency (MVHF) plasma. We have monitored the light scattered from powder generated in the plasma using an Ar-laser and a silicon photodiode. This simple, non-invasive technique allows us to make measurements on the same reactor used to make the solar cells. First, we have varied the total flow rate and observed a maximum in the scattered light intensity from powder in the plasma during the deposition of the intrinsic layer, and correlated this with the degradation, as well as the stabilized performance of the solar cells. Then, we have studied the effects of varying the deposition temperature and/or the addition of germane to the gas mixture on the scattered light intensity due to powder in the plasma.

Improved Back Reflector for High Efficiency Hydrogenated Amorphous and Nanocrystalline Silicon Based Solar Cells

2005 ◽  
Vol 862 ◽  
Author(s):  
Baojie Yan ◽  
Jessica M. Owens ◽  
Chun-Sheng Jiang ◽  
Jeffrey Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Light Intensity ◽  
Silicon Germanium ◽  
High Efficiency ◽  
Short Circuit ◽  
Scattered Light ◽  
Nanocrystalline Silicon ◽  
Scattered Light Intensity ◽  
Micro Features ◽  
Hydrogenated Amorphous

AbstractAg/ZnO back reflectors (BR) on specular stainless steel substrates are optimized for hydrogenated amorphous silicon germanium alloy (a-SiGe:H) and nanocrystalline silicon (nc-Si:H) solar cells. The BRs are deposited using a sputtering method. The texture of the Ag and ZnO layers is controlled by deposition parameters as well as chemical etching with diluted HCl. The surface morphology is investigated by atomic force microscopy. The scattered light intensity from a He-Ne laser, which illuminates the sample surface perpendicularly, is measured at different angles. Finally, a-SiGe:H and nc-Si:H solar cells are deposited on the BR substrates prepared under various conditions. For a-SiGe:H bottom cells, the improved BR with large micro-features leads to an enhanced open-circuit voltage. For the nc-Si:H solar cells, large micro-features on the improved BR eliminate interference fringes otherwise observed in the quantum efficiency measurement and result in high short circuit current density. The result is consistent with an enhanced scattered light intensity. Hence, the cell performance was improved. We also deposited a-Si:H/a-SiGe:H/nc-Si:H triple-junction cells on the optimized BR and achieved a high initial active-area efficiency of 14.6%.

Study of Large Area a-Si:H and nc-Si:H Based Multijunction Solar Cells and Materials

2008 ◽  
Vol 1066 ◽  
Author(s):  
Xixiang Xu ◽  
Baojie Yan ◽  
Dave Beglau ◽  
Yang Li ◽  
Greg DeMaggio ◽  
...  
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
Plasma Deposition ◽  
Nanocrystalline Silicon ◽  
High Rate ◽  
High Deposition Rate ◽  
Large Area ◽  
Very High Frequency ◽  
Spatial Uniformity ◽  
Double Junction

ABSTRACTSolar cells based on hydrogenated nanocrystalline silicon (nc-Si:H) have demonstrated significant improvement in the last few years. From the standpoint of commercial viability, good quality nc-Si:H films must be deposited at a high rate. In this paper, we present the results of our investigations on obtaining high quality nc-Si:H and a-Si:H films and solar cells over large areas using high deposition rate. We have employed the modified very high frequency (MVHF) glow discharge technique to realize high-rate deposition. Modeling studies were conducted to attain good spatial uniformity of electric field over a large area (15”×1”) MVHF cathode for nc-Si:H deposition. A comparative study has been carried out between the RF and MVHF plasma deposited a-Si:H and nc-Si:H single-junction and a-Si:H/nc-Si:H double-junction solar cells. By optimizing the nc-Si:H cell and the tunnel/recombination junctions, we have obtained an initial aperture-area (460 cm2) efficiency of 11.9% for a-Si:H/nc-Si:H double-junction cells using conventional RF (13.56 MHz) plasma deposition. The deposition rate was 3 Å/sec. Results on solar cells made with MVHF will also be presented.

scholarly journals Planar droplet sizing: Application to a spray of Jet A1 kerosene

2017 ◽  
Author(s):  
Pierre Doublet ◽  
Christine Lempereur ◽  
Virginel Bodoc ◽  
Mikael Orain ◽  
Pierre Gajan
Keyword(s):  
Light Intensity ◽  
Scattered Light ◽  
Droplet Surface ◽  
Scattered Light Intensity ◽  
Field Of View ◽  
Fluorescence Signal ◽  
Droplet Volume ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Scattering Angle

Optical techniques are  widely employed for their non-intrusive behavior and are applied to two-phase flowinvestigations. Until now, the most commonly used technique to determine the droplet size is the Phase Doppler Anemogranulometry, although it is time consuming for an overall injector characterization. An imaging technique called Planar Droplet Sizing has been used to offer an alternative and provide a spatially-resolved 2D map of the Sauter Mean Diameter (SMD). The measurement is based on the ratio between laser-induced fluorescence and scattered light intensities which are assumed to be proportional respectively to the droplet volume and droplet surface area. However, previous studies revealed that the dependence of fluorescence intensity on the droplet volume can be altered by the absorption of light in the liquid. The scattered light intensity depends on the scattering angle and intensity variations within the field of view must be avoided.The aim of this study is to make the PDS technique operational for a Jet A-1 kerosene spray. A strong absorption of liquid kerosene appears under UV excitation at 266 nm making the technique unsuitable. Under visible excitation at 532 nm, a fluorescent tracer (Pyrromethene 597) must be added to the kerosene to enhance the fluorescence signal. To prevent scattered light intensity variations within the field of view, an optimal scattering angle close to 115° is required. An image processing algorithm is proposed in order to reduce the effects ofmultiple scattering.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4698

scholarly journals Method for the Determination of Density and Phase Functions of Interplanetary Dust

1980 ◽  
Vol 90 ◽  
pp. 55-60
Author(s):  
A. Mujica ◽  
G. Lôpez ◽  
F. Sánchez
Keyword(s):  
Light Intensity ◽  
Unit Volume ◽  
Interplanetary Space ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Scattered Light Intensity ◽  
Zodiacal Light ◽  
Method Of Determination ◽  
Phase Functions

SummaryA method of determination of the scattered light intensity, , by a unit-volume of interplanetary space is presented. From ground base Zodiacal Light measurements and the experimental results of Pioneer X the density, ρ(r), and phase, σ(θ), functions are obtained without any previous assumptions about them.

scholarly journals Optimum Angles for Multi-Angle Elastic Light Scattering Experiments

2011 ◽  
Author(s):  
D. W. Burr ◽  
K. J. Daun ◽  
K. A. Thomson ◽  
G. J. Smallwood
Keyword(s):  
Inverse Problem ◽  
Light Scattering ◽  
Light Intensity ◽  
Size Distribution ◽  
Design Of Experiment ◽  
Scattered Light ◽  
Scattered Light Intensity ◽  
Elastic Light Scattering ◽  
Optimal Angle ◽  
Ill Posed

In multiangle elastic light scattering (MAELS) experiments, the morphology of aerosolized particles is inferred by shining collimated radiation through the aerosol and then measuring the scattered light intensity over a set of angles. In the case of soot-laden aerosols MAELS can be used to recover, among other things, the size distribution of soot aggregates. This involves solving an ill-posed set of equations, however. While previous work focused on regularizing the inverse problem using Bayesian priors, this paper presents a design-of-experiment methodology for identifying the set of measurement angles that minimizes its ill-posedness. The inverse problem produced by the optimal angle set requires less regularization and is less sensitive to noise, compared with two other measurement angle sets commonly used to carry out MAELS experiments.

High Efficiency Large Area a-Si:H and a-SiGe:H Multi-junction Solar Cells Using MVHF at High Deposition Rate

2009 ◽  
Vol 1153 ◽  
Author(s):  
Xixiang Xu ◽  
Dave Beglau ◽  
Scott Ehlert ◽  
Yang Li ◽  
Tining Su ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
High Deposition Rate ◽  
Discharge Process ◽  
Large Area ◽  
Very High Frequency ◽  
Cell Structures ◽  
Evolution Characteristics ◽  
Stable Performance ◽  
Sun Light

AbstractWe have developed high efficiency large area a-Si:H and a-SiGe:H multi-junction solar cells using a Modified Very High Frequency (MVHF) glow discharge process. We conducted a comparative study for different cell structures, and compared the initial and stable performance and light-induced degradation of solar cells made using MVHF and RF techniques. Besides high efficiency, the MVHF cells also demonstrate superior light stability, showing <10% degradation after 1000 hour of one-sun light soaking at 50 °C. We also studied light-induced defect level and hydrogen evolution characteristics of MVHF deposited a-SiGe:H films and compared them with the RF deposited films.

Opalescence and concentration fluctuations in binary liquid mixtures near the critical mixing point. - II. Theoretical

1954 ◽  
Vol 224 (1156) ◽  
pp. 104-119 ◽  
Keyword(s):  
Correlation Function ◽  
Light Intensity ◽  
Scattered Light ◽  
Wave Length ◽  
Liquid Mixtures ◽  
Density Fluctuations ◽  
Concentration Fluctuations ◽  
Scattered Light Intensity ◽  
Gaussian Shape ◽  
Critical Mixing

A theory of light scattering in fluids produced by local fluctuations of refractive index is developed from the theory of X-ray scattering in fluids which is applied to the phenomena of critical opalescence in one-component liquids due to density fluctuations and in two-component liquid mixtures due to concentration fluctuations. The dependence of the scattered light intensity on wave-length and scattering angle can be derived from the theoretical expressions when the correlation of the fluctuations in two volume elements as a function of the distance of these elements is known. The theory is used for determining the shape of the correlation function for a number of binary mixtures from the measured angular distribution of the scattered light intensity, as described in part I by means of numerical computation of Fourier integrals. It is found that the mixtures belonging to class I (as defined in part I) are characterized by a correlation function with a range of negative correlation, and those belonging to class II by a correlation function of nearly Gaussian shape. The absolute magnitude of the concentration fluctuations near the critical mixing point is also calculated from the observational material. A tentative qualitative explanation for the different shapes of the correlation function for the two classes of mixtures is presented.

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