Grain Growth and Mobility in Nanocrystalline Ge Films

2012 ◽  
Vol 1426 ◽  
pp. 359-364
Author(s):  
Siva Konduri ◽  
Max Noack ◽  
Vikram Dalal
Keyword(s):  
Grain Size ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Deposition Pressure ◽  
High Hydrogen ◽  
Strong Function ◽  
X Ray ◽  
Grain Sizes ◽  
Frequency Plasma ◽  
Hydrogen Mixtures

ABSTRACTIn this paper, we report on deposition and properties of nanocrystalline Ge:H films . The films were grown from germane and hydrogen mixtures using Radio frequency Plasma-enhanced chemical vapor deposition (RF-PECVD) process using ∼45 MHz frequency. The crystallinity of the films was measured using Raman measurements and from x-ray diffraction techniques, it was found that the grain size was a strong function of deposition pressure, temperature and hydrogen/germane ratios. High hydrogen ratios and high powers led to films with smaller grains. Higher pressures and smaller hydrogen/germane ratio led to films with larger grain sizes, as did higher growth temperatures. The mobility of electrons and holes was measured using space charge limited current (SCLC) techniques in n+-n-n+ devices. It was found that nominally undoped films were generally n type with carrier concentrations in the 1E14/cm3 range. Mobility was found to increase with grain size, with 60 nm grains showing mobility in the 2-3 cm2/V-s range.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

Heterogeneity Effects in X-Ray Analysis*

1961 ◽  
Vol 5 ◽  
pp. 335-354 ◽  
Author(s):  
Fernand Claisse ◽  
Claude Samson
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Mathematical Treatment ◽  
Grain Size Effect ◽  
Light Elements ◽  
X Ray Diffraction ◽  
Limited Region ◽  
X Ray ◽  
Grain Sizes ◽  
Heterogeneity Effects

AbstractA fundamental quantitative treatment of the heterogeneity effects in X-ray fluorescence has been made. The theory predicts that the grain-size effect appears only in a limited region of grain sizes which depends on the wavelength of the primary radiation and the nature of the compounds in the mixture. With monochromatic radiation, the fluorescence intensity showed increase or decrease by a factor of a few units as grain size is decreased, A factor as large as 12, the theoretical value, has been observed in one particular experiment. Usually the grain-size effect can be eliminated by intensive grinding. For the light elements fine grinding is disastrous if long wavelengths are used. By an appropriate choice of the wavelength it is possible to eliminate the effect even without grinding. The mathematical treatment also predicts, but less rigorously, a grain-size effect in X-ray diffraction.The effect on the fluorescence intensities by changes in the chemical composition of the grains that contain the fluorescent element is predicted by the theory.These findings are discussed in relation to the analysis of elements when polychromatic beams are used.

Compamson in the Growth and Properties of rf Sputtered μc-Si:H and Glow Discharge-Chemical Vapor Deposited μc-Si:H Films

1993 ◽  
Vol 321 ◽  
Author(s):  
J. Y. Lin ◽  
B. H. Tseng ◽  
K. C. Hsu ◽  
H. L. Hwang
Keyword(s):  
Glow Discharge ◽  
Rf Sputtering ◽  
Chemical Vapor ◽  
Treatment Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Chemical Vapor Deposited ◽  
Ft Ir ◽  
Almost All

ABSTRACTProperties of μc-Si:H films grown by rf sputtering and by glow discharge-chemical vapor deposition (GD-CVD) using diluted-hydrogen and hydrogen-atom-treatment method were compared employing TEM, X-ray diffraction, Raman scattering and FT-IR. The films deposited by both methods all exhibited comparable grain sizes in the range of 10–18 nm. and showed the same tendency in almost all the Measurements.

Dislocations in Submicron Grain Size and Nanocrystalline Copper

2000 ◽  
Vol 634 ◽  
Author(s):  
T. Ungár ◽  
G. Tichy ◽  
P. G. Sanders ◽  
J. R. Weertman
Keyword(s):  
Grain Size ◽  
Profile Analysis ◽  
Dislocation Model ◽  
X Ray Diffraction ◽  
Strain Anisotropy ◽  
Nanocrystalline Copper ◽  
X Ray ◽  
Gas Condensation ◽  
Grain Sizes ◽  
20 Nm

ABSTRACTUsing the dislocation model of strain anisotropy in X-ray diffraction peak profile analysis it is shown that in nanocrystalline copper produced by inert gas condensation dislocations are present, at least, down to average grain sizes of the order of 20 nm. Based on the analysis of the dislocation contrast factors it is suggested that with decreasing grain size the proportion of Lomer-Cottrell type dislocations increases.

Study of Machining-Induced Microstructure Variations of Nanostructured/Ultrafine-Grained Copper Using XRD

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Yong Huang ◽  
Mason Morehead
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Dislocation Density ◽  
Equal Channel Angular Extrusion ◽  
Outer Radius ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Area And Volume

Various methods for the production of bulk nanostructured (NS)/ultrafine-grained (UFG) materials have been developed, including equal channel angular extrusion (ECAE), a form of severe plastic deformation. Using an ECAE NS/UFG copper bar as an example, this study has investigated machining-induced workpiece microstructure variation using X-ray diffraction. It has been found that (1) under gentle cutting conditions, there was a 10% increase in the median grain size compared with unmachined ECAE NS/UFG copper bars. Increases in the arithmetic-, area-, and volume-weighted grain sizes were found to be 10%, 8%, and 8%, respectively, and (2) an average 27% drop in the dislocation density was observed between the machined and unmachined ECAE copper bars. The dislocation density was shown to have the most reduction (−39%) at the outer radius of the machined ECAE bar where more heat and/or higher pressure were experienced.

Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

Thermodynamic Stabilization of Grain Size in Nanocrystalline Metals

2012 ◽  
Vol 715-716 ◽  
pp. 323-328 ◽  
Author(s):  
Carl C. Koch ◽  
Ron O. Scattergood ◽  
Brian K. VanLeeuwen ◽  
Kristopher A. Darling
Keyword(s):  
Grain Size ◽  
Annealing Temperature ◽  
Experimental Results ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Thermodynamic Stabilization ◽  
Solute Atoms ◽  
Zr Alloy

This paper describes the stabilization of nanocrystalline grain sizes in Pd and Fe by the addition of Zr solute atoms. The grain size as a function of annealing temperature was measured by both x-ray diffraction (XRD) line broadening analysis and microscopy methods. The latter methods showed that the XRD grain size measurements for the samples annealed at the higher temperatures were not valid. It appears that thermodynamic stabilization may still be operative in the Fe-4at.% Zr alloy but not in the Pd-19at.% Zr alloy from the experimental results and calculations of the enthalpy of segregation.

scholarly journals MOCVD of Very thin Films of Lead Lanthanum Titanate

1995 ◽  
Vol 415 ◽  
Author(s):  
David B. Beach ◽  
Catherine E. Vallet
Keyword(s):  
Perovskite Phase ◽  
Chemical Vapor ◽  
Precursor Solution ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Lanthanum Titanate ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

ABSTRACTFilms of lead lanthanum titanate were deposited using metal-organic chemical vapor deposition (MOCVD) at temperatures between 500 and 550°C in a hot-wall reactor. The precursors used were Pb(THD)2, La(THD)3, and Ti(THD)2(I-OPr)2where THD = 2,2,6,6-tetramethyl-3,5-heptanedionate, O2C11H19, and I-OPr = isopropoxide, OC3H7. The three precursors were delivered to the reactor using a single solution containing all three precursors dissolved in tetraglyme and the precursor solution was volatilized at 225°C. Films were deposited on Si and Si/Ti/Pt substrates, and characterized using Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction(XRD). Films deposited at 550°C had a composition which was close to that of the precursor solution while films deposited at 500°C were deficient in lanthanum. Even at 500°C, the desired perovskite phase is readily observed by XRD. Subsequent rapid thermal processing of the film deposited at 500°C showed an increase in the intensity of the X-ray lines, but did not change the width of these lines, implying that grain sizes had remained unchanged.

Mg-doped N-polar InN Grown by RF-MBE

2006 ◽  
Vol 955 ◽  
Author(s):  
Daisuke Muto ◽  
Hiroyuki Naoi ◽  
Shinya Takado ◽  
Hyunseok Na ◽  
Tsutomu Araki ◽  
...  
Keyword(s):  
Grain Size ◽  
X Ray Diffraction ◽  
Doping Amount ◽  
X Ray ◽  
Mg Doping ◽  
Surface Migration ◽  
Frequency Plasma ◽  
Growth Properties ◽  
Hall Effect Measurements ◽  
Mg Doped

ABSTRACTWe have investigated the growth properties of Mg-doped N-polar InN films grown by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). We found that the Mg-doped InN films had smaller grain size than non-doped films, and furthermore the grain size decreased with an increase in Mg doping amount. Non-doped InN exhibited a single X-ray diffraction (XRD) peak of (0002) h-InN. On the other hand, the Mg-doped InN produced a weak XRD peak of (111) c-InN in addition to a strong peak of (0002) h-InN. These results indicate that the Mg doping decreased the surface migration length of In atoms. From Hall-effect measurements, all the samples were shown to have n-type conductivity. Mg-doped InN grown with Mg cell temperatures of 130 and 135°C had carrier concentrations that were about half (i.e., ∼4.5×1018 cm−3) that of the non-doped InN. However, the carrier concentration tended to increase with further supply of Mg. These results indicate that Mg-doping causes a trade-off between a carrier decreasing effect from the Mg acceptors and a carrier increasing effect from defects caused by the poor surface migration of In atoms.

A CRYSTAL STRUCTURE STUDY OF La1-xCaxMnO3 NANOPARTICLES

2004 ◽  
Vol 18 (12n13) ◽  
pp. 597-602 ◽  
Author(s):  
YINGWEN DUAN ◽  
JIANGONG LI
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Surface Effect ◽  
Sol Gel ◽  
Structure Study ◽  
X Ray Diffraction ◽  
Structure Transition ◽  
X Ray ◽  
Grain Sizes ◽  
Average Grain Size

Using a sol-gel method, La 1-x Ca x MnO 3(0≤x≤0.5) nanoparticles with nearly the same average grain size of about 21 nm and different Ca contents, La 0.8 Ca 0.2 MnO 3 nanoparticles with various average grain sizes were prepared. Crystal structure was investigated by X-ray diffraction. Increasing Ca content and decreasing grain size can lead to the average Mn–O bond lengths decrease and Mn–O–Mn bond angles increase. The crystal symmetry changes from orthorhombic to cubic as x≥0.3 for the La 1-x Ca x MnO 3(0≤x≤0.5) nanoparticles with nearly the same average grain size and D~16 nm for the La 0.8 Ca 0.2 MnO 3 nanoparticles with various grain sizes. Small-size effect and surface effect may be the reasons of the lattice distortion and structure transition.

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