Grain-size distributions and grain boundaries of chalcopyrite-type thin films

2007 ◽  
Vol 40 (5) ◽  
pp. 841-848 ◽  
Author(s):  
D. Abou-Ras ◽  
S. Schorr ◽  
H. W. Schock
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Distribution Functions ◽  
Size Distributions ◽  
Twin Boundaries ◽  
Solar Absorbers ◽  
Grain Size Distributions ◽  
Backscatter Diffraction

CuInSe2, CuGaSe2, Cu(In,Ga)Se2and CuInS2thin-film solar absorbers in completed solar cells were studied in cross section by means of electron-backscatter diffraction. From the data acquired, grain-size distributions were extracted, and also the most frequent grain boundaries were determined. The grain-size distributions of all chalcopyrite-type thin films studied can be described well by lognormal distribution functions. The most frequent grain-boundary types in these thin films are 60°−〈221〉tetand 71°−〈110〉tet(near) Σ3 twin boundaries. These results can be related directly to the importance of {112}tetplanes during the topotactical growth of chalcopyrite-type thin films. Based on energetic considerations, it is assumed that the most frequent twin boundaries exhibit a 180°−〈221〉tetconstellation.

Characterization of Sputtered CdTe Thin Films with Electron Backscatter Diffraction and Correlation with Device Performance

2015 ◽  
Vol 21 (4) ◽  
pp. 927-935 ◽  
Author(s):  
Matthew M. Nowell ◽  
Michael A. Scarpulla ◽  
Naba R. Paudel ◽  
Kristopher A. Wieland ◽  
Alvin D. Compaan ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Electrical Performance ◽  
Poor Correlation ◽  
Twin Boundaries ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractThe performance of polycrystalline CdTe photovoltaic thin films is expected to depend on the grain boundary density and corresponding grain size of the film microstructure. However, the electrical performance of grain boundaries within these films is not well understood, and can be beneficial, harmful, or neutral in terms of film performance. Electron backscatter diffraction has been used to characterize the grain size, grain boundary structure, and crystallographic texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with microstructure. Weak fiber textures were observed in the as-deposited films, with (111) textures present at lower deposition pressures and (110) textures observed at higher deposition pressures. The CdCl2-treated samples exhibited significant grain recrystallization with a high fraction of twin boundaries. Good correlation of solar cell efficiency was observed with twin-corrected grain size while poor correlation was found if the twin boundaries were considered as grain boundaries in the grain size determination. This implies that the twin boundaries are neutral with respect to recombination and carrier transport.

Preferred Orientation, Grain Sizes and Grain Boundaries of Chalcopyrite-Type Thin Films

2007 ◽  
Vol 1012 ◽  
Author(s):  
Daniel Abou-Ras ◽  
Melanie Nichterwitz ◽  
Christian A. Kaufmann ◽  
Susan Schorr ◽  
Hans-Werner Schock
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Fiber Texture ◽  
Distribution Functions ◽  
X Ray Diffraction ◽  
Grain Sizes ◽  
Grain Orientations ◽  
Grain Size Distributions ◽  
Backscatter Diffraction

AbstractChalcopyrite-type thin films - CuInS2, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2 - in various completed solar cells were studied in cross-section by means of electron-backscatter diffraction (EBSD). Valuable information on grain sizes, local grain orientations, film textures, and grain boundaries were extracted from the EBSD linescans and maps. The grain-size distributions from the chalcopyrite-type thin films can be represented well by lognormal distribution functions. The EBSD measurements on CuGaSe2 thin film reveal a <110> fiber texture, in good agreement with x-ray diffraction texture analysis performed on the same sample. The EBSD maps from all samples studied exhibit considerable twinning in the chalcopyrite-type thin films. Indeed, the most frequent types of grain boundaries in these thin films are (near) Σ3 60°-<221> and 71°-<110> twins. It is shown that rotational 180°-<221> twins (which are symmetrically equivalent to 71°-<110>) are more frequently found than anion- or cation-terminated 60°-<221> twin boundaries.

Orientationally Resolved Grain Size Distributions in Thin Films

1998 ◽  
Vol 273-275 ◽  
pp. 237-242 ◽  
Author(s):  
J. Greiser ◽  
Peter Müllner ◽  
E. Arzt
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Size Distributions ◽  
Grain Size Distributions

Strengthening metals by narrowing grain size distributions in nickel-titanium thin films

2013 ◽  
Vol 28 (10) ◽  
pp. 1289-1294 ◽  
Author(s):  
Xu Huang ◽  
David T. Wu ◽  
Derek Zhao ◽  
Ainissa G. Ramirez
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Nickel Titanium ◽  
Size Distributions ◽  
Grain Size Distributions ◽  
Titanium Thin Films ◽  
Image Position

Abstract

Numerical Modelling of Spray Formed Grain Size Evolution

2007 ◽  
Vol 561-565 ◽  
pp. 1991-1994 ◽  
Author(s):  
Jia Wei Mi ◽  
Patrick S. Grant
Keyword(s):  
Grain Size ◽  
Electron Backscatter Diffraction ◽  
Droplet Size Distribution ◽  
Spray Forming ◽  
Liquid Droplets ◽  
Alloy Droplet ◽  
Size Evolution ◽  
Grain Size Distributions ◽  
Backscatter Diffraction ◽  
Droplet Spray

A numerical model has been developed to simulate the distribution of polygonal grain size in a sprayed microstructure formed from an alloy droplet spray containing a large number of solid, mushy and liquid droplets. The model takes into account the effects of: (1) the droplet size distribution; (2) its corresponding distribution of solid, mushy and liquid droplets at the instant of deposition; (3) the overall thermal condition of the spray formed preform during final solidification. The model has been validated against experiments of the spray forming of Ni superalloy rings, with modelled grain size distributions giving good agreement with measurements obtained by electron backscatter diffraction.

scholarly journals Grain Growth Anomaly in Ti-rich Strontium Titanate as Revealed by Electron Microscopy

2012 ◽  
Vol 18 (S5) ◽  
pp. 123-124
Author(s):  
L. Amaral ◽  
M. Fernandes ◽  
A. M. R. Senos ◽  
P. M. Vilarinho ◽  
M. P. Harmer
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Strontium Titanate ◽  
Structural Changes ◽  
Sintering Temperature ◽  
Size Distributions ◽  
High Tunability ◽  
Grain Size Distributions

An anomaly in the dependence of the kinetics of grain growth on the temperature for strontium titanate (ST) ceramics is reported in this work. It consists of a decrease of the grain size with increasing sintering temperature. Recently, a drop in the grain boundary mobility of ST in the same temperature range was reported. These observations imply an unusual decrease of the grain size with the increase of the sintering temperature, in agreement with our present results. Although the mobility drop was related to structural changes in grain boundaries, the exact mechanism involved is still unknown. The understanding of this anomaly may offer an alternative way of controlling the microstructure and tuning the dielectric response of ST based compositions without the use of dopants. ST is characterized by high dielectric permittivity, high tunability and low dielectric losses, and is thus a particularly interesting material for capacitor or tunable microwave devices. These properties are very dependent on the stoichiometry, structure and microstructure, in which the role of grain boundaries is fundamentally important. Indeed, increasing attention has been paid to grain boundary structures and nonstoichiometry and to its relation with microstructure and electrical properties. Densification proceeds faster with decreasing Sr/Ti ratio (Ti-rich compositions). Sr-rich samples show narrow grain size distributions, while Ti excess favors enlarged grain size distributions and faceting of the grain boundaries.

Grain Growth in Al-(Cu, Pd, Nb) Thin Films

1993 ◽  
Vol 309 ◽  
Author(s):  
J.D. Mis ◽  
K.P. Rodbell
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Growth ◽  
Weight Percent ◽  
Size Distributions ◽  
Precipitate Morphology ◽  
X Ray ◽  
Transmission Electron ◽  
Grain Size Distributions

AbstractThe microstructure of 1 μim thick Al films containing 0.5 and 2%Cu (weight percent), 0.3%Pd, and 0.3%Pd-0.3%Nb were investigated by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS) as a function of isochronal and isothermal anneals. The grain size, grain size distribution, and precipitate morphology of these films was measured from 200 to 500ºC, with the activation energy for grain growth (Ea) determined for I h anneals at 200, 300, 400 and 500ºC. Normal grain growth was recorded for the A1Cu films annealed at temperatures ≤400ºC; however secondary grain growth occurred in the AI-2Cu film annealed for I h at 500ºC, with grains as large as 16 μm in diameter observed. Grain growth in the AI-0.3Pd films resulted in strongly bi-modal grain size distributions, with the onset ofsignificant grain growth retarded for I h anneals at temperatures ≤300ºC.The addition of Nb to the AI-0.3Pd film resulted in monomodal grain size distributions over the entire temperature range. The role of crystallographic texture on grain growth in thin films is discussed.

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