Evaluation of Pore Structure in Pure Silica Zeolite MFI Low-kThin Films Using Positronium Annihilation Lifetime Spectroscopy

2004 ◽  
Vol 108 (31) ◽  
pp. 11689-11692 ◽  
Author(s):  
Shuang Li ◽  
Jianing Sun ◽  
Zijian Li ◽  
Huagen Peng ◽  
David Gidley ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pure Silica ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

scholarly journals Revealing hidden pore structure in nanoporous thin films using positronium annihilation lifetime spectroscopy

2005 ◽  
Vol 86 (12) ◽  
pp. 121904 ◽  
Author(s):  
Hua-Gen Peng ◽  
William E. Frieze ◽  
Richard S. Vallery ◽  
David W. Gidley ◽  
Darren L. Moore ◽  
...  
Keyword(s):  
Thin Films ◽  
Pore Structure ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

Electrical, Mechanical, and Structural Properties of Fluoro-Containing Poly(silsesquioxanes) Based Porous Low k Thin Films

2003 ◽  
Vol 766 ◽  
Author(s):  
Jingyu Hyeon-Lee ◽  
Jihoon Rhee ◽  
Jungbae Kim ◽  
Jin-Heong Yim ◽  
Seok Chang
Keyword(s):  
Thin Films ◽  
Pore Size ◽  
Dielectric Constants ◽  
Commercial Application ◽  
Porous Films ◽  
Low Dielectric ◽  
Nanoporous Films ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy ◽  
Low K

AbstractLow dielectric fluoro-containing poly(silsesquioxanes) (PSSQs) have been synthesized using trifluoropropyl trimethoxysilane (TFPTMS), methyl trimethoxysilane (MTMS), and 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetra(trimethoxysilylethyl) cyclotetrasiloxane. The properties of fluorocontaining PSSQs based thin films were studied by electrical, mechanical, and structural characterization. Film was spun on a silicon substrate, baked at 150°C and 250°C for 1 minute, respectively, and cured in the furnace at 420°C for 1 hour under vacuum condition. Thermally decomposable trifluoropropyl groups of the fluoro-containing PSSQ were served as a pore generator and partially contributed to lower a dielectric constant. â-cyclodextrin (CD) was also employed as a pore generator. The concentration of the pore generator in the film was varied from 0 to 30 %. The dielectric constants of the porous PSSQ films were found to be in the range of 2.7 – 1.9 (at 100 kHz). Hardness and Young's modulus of the films were measured by nano-indentation. The elastic modulus and hardness of the porous films were well correlated with the concentration of the pore generators. Positronium Annihilation Lifetime Spectroscopy (PALS) was employed to characterize a pore size of the porous fluoro-containing PSSQ film. The pore size of the film was less than 2.2 nm. The nanoporous films showed quite promising properties for commercial application.

Characterizing Porosity in Nanoporous Thin Films Using Positronium Annihilation Lifetime Spectroscopy

2002 ◽  
Vol 726 ◽  
Author(s):  
J.N. Sun ◽  
D. W. Gidley ◽  
Y.F. Hu ◽  
W.E. Frieze ◽  
S. Yang
Keyword(s):  
Pore Size ◽  
Size Distribution ◽  
Depth Profiling ◽  
Positron Beam ◽  
Bound State ◽  
Hybrid Films ◽  
Porous Films ◽  
Pore Characteristics ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

AbstractDepth profiled positronium annihilation lifetime spectroscopy (PALS) has been used to probe the pore characteristics (size, distribution, and interconnectivity) in thin, porous films, including silica, organic and hybrid films. PALS has good sensitivity to and resolution of all pores (both interconnected and closed) in the size range from 0.3 nm to 30 nm, even in films buried under a diffusion barrier. In this technique a focussed beam of several keV positrons forms positronium (Ps, the electron-positron bound state) with a depth distribution that depends on the selected positron beam energy. Ps inherently localizes in the pores where its natural (vacuum) annihilation lifetime of 142 ns is reduced by collisions with the pore surfaces. The collisionally reduced Ps lifetime is correlated with pore size and is the key feature in transforming a Ps lifetime distribution into a pore size distribution. In hybrid films made porous by a degradable porogen PALS readily detects a percolation threshold with increasing porosity that represents the transition from closed pores to interconnected pores. PALS is a non-destructive, depth profiling technique with the only requirement that positrons can be implanted into the porous film where Ps can form.

Depth-profiled positronium annihilation lifetime spectroscopy on porous films

2007 ◽  
Vol 300 (1-2) ◽  
pp. 154-161 ◽  
Author(s):  
Hua-Gen Peng ◽  
Richard S. Vallery ◽  
Ming Liu ◽  
Mark Skalsey ◽  
David W. Gidley
Keyword(s):  
Porous Films ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

Probing Pore Characteristics in Low-K Thin Films Using Positronium Annihilation Lifetime Spectroscopy

2000 ◽  
Vol 612 ◽  
Author(s):  
D. W. Gidley ◽  
W. E. Frieze ◽  
T. L. Dull ◽  
J. N. Sun ◽  
A. F. Yee
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Gas Absorption ◽  
Porous Films ◽  
Pore Characteristics ◽  
Average Pore ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

AbstractDepth profiled positronium annihilation lifetime spectroscopy (PALS) has been used to probe the pore characteristics (size, distribution, and interconnectivity) in thin, porous films, including silica and organic-based films. The technique is sensitive to all pores (both interconnected and closed) in the size range from 0.3 nm to 300 nm, even in films buried under a diffusion barrier. PALS may be particularly useful in deducing the pore-size distribution in closed-pore systems where gas absorption methods are not available. In this technique a focussed beam of several keV positrons forms positronium (Ps, the electron-positron bound state) with a depth distribution that depends on the selected positron beam energy. Ps inherently localizes in the pores where its natural (vacuum) annihilation lifetime of 142 ns is reduced by collisions with the pore surfaces. The collisionally reduced Ps lifetime is correlated with pore size and is the key feature in transforming a Ps lifetime distribution into a pore size distribution. In thin silica films that have been made porous by a variety of methods the pores are found to be interconnected and an average pore size is determined. In a mesoporous methyl-silsesquioxane film with nominally closed pores a pore size distribution has been determined. The sensitivity of PALS to metal overlayer interdiffusion is demonstrated. PALS is a non-destructive, depth profiling technique with the only requirement that positrons can be implanted into the porous film where Ps can form.

Positronium Annihilation Lifetime Spectroscopy of Porous Low-k Films with Periodic Pore Structures

2004 ◽  
Vol 445-446 ◽  
pp. 334-336 ◽  
Author(s):  
Toshiyuki Ohdaira ◽  
Ryoichi Suzuki ◽  
Hironobu Shirataki ◽  
Shin-Ya Matsuno
Keyword(s):  
Pore Structures ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy ◽  
Low K

Determining Pore Structure and Growth Mechanisms in Templated Nanoporous Low-k Films

2005 ◽  
Vol 863 ◽  
Author(s):  
Hua-Gen Peng ◽  
Richard S. Vallery ◽  
Ming Liu ◽  
William E. Frieze ◽  
David W. Gidley ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pore Size ◽  
Host Matrix ◽  
3 Dimensional ◽  
Nanoporous Films ◽  
Size Growth ◽  
Positronium Annihilation Lifetime Spectroscopy ◽  
The Relationship ◽  
Low K

AbstractTemplating is one of the most popular methods for generating nanocomposite and nanoporous films and the resultant pore size and pore interconnection length depend strongly on porogen concentration/porosity among other factors. Positronium Annihilation Lifetime Spectroscopy (PALS) analysis has been performed on a series of films produced using increasing concentrations of a type of cyclodextrin (CD) porogen in a modified silsesquioxane host matrix. PALS reveals the relationship between the resulting pore structure (both size and interconnection length) and porosity, which can be used to deduce pore shape. At low porogen concentration, isolated pores are resolved, but the pore size is consistent with a cluster of two or three CD molecules, rather than an individual one. As the porosity increases, the aggregation of the porogen domains appears to be more 3-dimensional (pseudo-random) with gradual increase in pore size. Computer simulations using a random pore growth model show consistent trends for pore size growth, but the agreement is poor for interconnection length. It is a key demonstration of the usefulness of PALS in untangling the fundamental pore structure and its evolution in porosity. PALS characterization of porosity provides novel feedback in the understanding and design of nanoporous materials.

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