H Evolution from Nano-Crystalline Silicon- Comparison of Simulation and Experiment

2004 ◽  
Vol 808 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pan
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Crystalline Silicon ◽  
Nanocrystalline Silicon ◽  
Temperature Peak ◽  
Nano Crystalline ◽  
Crystallite Surface ◽  
Excess Density ◽  
Simulation And Experiment ◽  
Higher Temperature

ABSTRACTThe temperature dependent H evolution from a-Si:H provides unique information on the H-bonding and microstructure. Traditional undiluted a-Si:H films show a high temperature H-evolution peak near 600°C. However device-quality compact nanocrystalline silicon films grown near the phase boundary of amorphous and microcrystalline growth show a new low temperature H- evolution peak near 400°C in addition to a second high temperature peak near 600°C. The origin of this peak cannot be attributed to microvoids or a substantial density of dihydride species typical of porous low-temperature films. We have simulated the H evolution using a molecular dynamics generated model of nanocrystalline silicon, where nano-crystallites reside in a background amorphous matrix. An excess density of H occurs at the crystallite surface. We find a low temperature evolution peak at 250-400°C, where the H-evolution starts from the surface of the nano-crystallite. In addition there is a higher temperature peak at 700-800°C providing good agreement with H-evolution measurements. The mobile H is found to exist in both the bond-centered type of species and H2 molecules – which has implications for H-diffusion models.

Atomistic Character of Nanocrystalline and Mixed Phase Silicon

2003 ◽  
Vol 762 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pan
Keyword(s):  
Crystalline Silicon ◽  
Electronic Band Structure ◽  
Nanocrystalline Silicon ◽  
Distribution Functions ◽  
Mixed Phase ◽  
Electronic Band ◽  
Nano Crystalline ◽  
Excess Density ◽  
Heterogeneous Phase ◽  
The Stability

AbstractMaterials grown close to the phase boundary of amorphous and microcrystalline growth have the best electronic properties for solar cells. Systematic molecular dynamics methods have generated such nano-crystalline silicon, consisting of a mixed phase of nano-crystallites in an amorphous matrix, using an embedding method. An excess density of H resides on the surface of the nanocrystallites. The structure of this heterogeneous phase will be characterized by atomic distribution functions and structure factors. The electronic band structure of smaller models of nanocrystalline silicon reveals no midgap states and is similar to a-Si:H. There is a highly strained region surrounding the crystallites. The presence of localized strain region may increase the stability of the material.

Early-life temperature modifies adult encapsulation response in an invasive ectoparasite

Parasitology ◽  
2015 ◽  
Vol 142 (10) ◽  
pp. 1290-1296 ◽  
Author(s):  
SIRPA KAUNISTO ◽  
LAURA HÄRKÖNEN ◽  
MARKUS J. RANTALA ◽  
RAINE KORTET
Keyword(s):  
Climate Change ◽  
High Temperature ◽  
Low Temperature ◽  
Blood Feeding ◽  
Life Cycles ◽  
Extreme Weather Events ◽  
Favourable Effect ◽  
Temperature Peak ◽  
Long Term Effects ◽  
High Temperature Peak

SUMMARYImmunity of parasites has been studied amazingly little, in spite of the fact that parasitic organisms, especially the arthropod parasites, need immunity to survive their own infections to successfully complete life cycles. Long-term effects of challenging environmental temperatures on immunity have remained unstudied in insects and parasites. Our study species, the deer ked (Lipoptena cervi; Linnaeus 1758), is an invasive, blood-feeding parasitic fly of cervids. Here, it was studied whether thermal stress during the pupal diapause stage could modify adult immunity (encapsulation capacity) in L. cervi. The effect of either a low temperature or high temperature peak, experienced during winter dormancy, on encapsulation response of active adult was tested. It was found that low temperature exposure during diapause, as long as the temperature is not too harsh, had a favourable effect on adult immunity. An abnormal, high temperature peak during pupal winter diapause significantly deteriorated the encapsulation capacity of emerged adults. The frequency and intensity of extreme weather events such as high temperature fluctuations are likely to increase with climate change. Thus, the climate change might have previously unknown influence on host-ectoparasite interactions, by affecting ectoparasite's immune defence and survival.

Search for High Damping Metallic Glasses

2006 ◽  
Vol 319 ◽  
pp. 151-156 ◽  
Author(s):  
Y. Hiki ◽  
M. Tanahashi ◽  
Shin Takeuchi
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Internal Friction ◽  
Metallic Glass ◽  
Room Temperature ◽  
Temperature Stability ◽  
Temperature Peak ◽  
High Temperature Side ◽  
Side Slope ◽  
Temperature Side

In a hydrogen-doped metallic glass, there appear low-temperature and high-temperature internal friction peaks respectively associated with a point-defect relaxation and the crystallization. The high-temperature-side slope of low-temperature peak and also the low-temperature-side slope of high-temperature peak enhance the background internal friction near the room temperature. A hydrogen-doped Mg-base metallic glass was proposed as a high-damping material to be used near and somewhat above the room temperature. Stability of the high damping was also checked.

The low-temperature barium fluoridozirconate variety α-BaZr2F10

2019 ◽  
Vol 75 (11) ◽  
pp. 1482-1487
Author(s):  
Jean-Paul Laval
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Structure Type ◽  
Higher Temperature

The low-temperature triclinic variety α-BaZr2F10 constitutes a new structure type, less symmetrical than the higher-temperature β-variety. It is based on the stacking of double sheets of Zr polyhedra, connecting three different kinds of ZrF7 polyhedra and one ZrF8 polyhedron via vertices and edges, separated by corrugated Ba2+ layers. It is compared to the high-temperature β-variety, directly recrystallizing from barium fluoridozirconate glass, and also to BaTe2F10 and KTe2F9.

Review Status on High Temperature Heat Pumps

2012 ◽  
Vol 170-173 ◽  
pp. 2550-2553 ◽  
Author(s):  
Guang Hui Zhou ◽  
Shi Wei Feng ◽  
Si Qi Cui ◽  
Yin Liu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Heat Pump ◽  
Heat Pumps ◽  
Industrial Processes ◽  
Paper Briefly ◽  
Development Status ◽  
Temperature Heat ◽  
Waste Energy ◽  
Higher Temperature

A heat pump is a kind of energy saving equipment. It can effectively improve the grade of low temperature renewable and waste energy. Because of the increasing demands for higher temperature energy in many industrial processes and other fields, the development and research of high temperature heat pumps have been becoming more and more pressing and significant. This paper briefly summarizes the development status in two aspects: the development of working fluids and system features and characteristics of different cycle types.

Key Technologies of Heterojunction Solar Cell and Module Manufacturing

2015 ◽  
Vol 1771 ◽  
pp. 25-32
Author(s):  
Xiangheng He ◽  
Tingkai Li
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Temperature ◽  
Low Temperature ◽  
Thin Layer ◽  
Mass Production ◽  
Power Loss ◽  
Laboratory Research ◽  
Key Technologies ◽  
Higher Temperature

ABSTRACTThe a-Si/c-Si Heterojunction Technology (HJT) or Heterojunction with intrinsic thin layer (HIT) solar cell have been fabricated in mass production，the average conversion efficiency of HJT solar cells with 3 bus bar, 5 bus bar and smart wire structures have reached 20%, 21% and 22% respectively. One of the biggest obstructions for HIT module manufacturing is the Cell-to-Module (CTM) stringing process where much power loss happened due to high temperature. The higher temperature in stringing process makes passivation quality worse and introduces much more defects. In this article, we present our investigation on CTM string connection methods, especially on which undergo low temperature to avoid thermal micro damage on cell’s functional structure. Several kinds of string connection are elaborated. The discussion will give some directions for further laboratory research and HJT manufacturing.

Effects of Various Hydrogen Dilution Ratios on the Performance of Thin Film Nanocrystalline/Crystalline Silicon Solar Cells

1998 ◽  
Vol 536 ◽  
Author(s):  
Y. J. Song ◽  
W. A. Anderson
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Electron Cyclotron Resonance ◽  
Crystalline Silicon ◽  
Low Cost ◽  
Silicon Film ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Maximum Efficiency ◽  
Crystalline Silicon Solar Cells

AbstractLow temperature growth of hydrogenated nanocrystalline silicon film (nc-Si:H) by microwave electron cyclotron resonance chemical vapor deposition has been performed employing a double dilution of silane, using a He carrier for SiH4 and its subsequent dilution by H2. A series of Raman spectra and AFM pictures has shown that a very thin (<100Å) nc-Si:H layer initially grown with high H2 dilution on a glass substrate can serve as a seed layer for the subsequent growth of the film with lower H2 dilution, which results in a higher crystallinity of the whole film. The role of this thin layer in low temperature junction formation has been examined by the insertion of the layer between the interface of both nc-Si:H (deposited with lower H2 dilution)/c-Si and a-Si:H/c-Si heterojunction type photovoltaic cells. This is to address the knowledge that the device's performance is strongly influenced by the quality of the thin film silicon/crystalline silicon interface. Various thicknesses and H2 dilution ratios have been used to find the optimized condition providing the best performance of the cells. The maximum efficiency of 10.5% (Jsc=35.1mA/cm2, Voc=0.51V and FF=0.59) has been obtained, without an AR coating, by the successive deposition of nc-Si:H film with four different H2 dilution ratios on a crystalline silicon substrate. This is potentially a low-temperature, low-cost solar cell fabrication process.

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