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.

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 Depth-profiling plasma-induced densification of porous low-k thin films using positronium annihilation lifetime spectroscopy

2002 ◽  
Vol 81 (8) ◽  
pp. 1447-1449 ◽  
Author(s):  
Jia-Ning Sun ◽  
David W. Gidley ◽  
Yifan Hu ◽  
William E. Frieze ◽  
E. Todd Ryan
Keyword(s):  
Thin Films ◽  
Depth Profiling ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy ◽  
Low K

Positron/positronium annihilation in nanocrystalline silicon thin films

1996 ◽  
Vol 211 (1) ◽  
pp. 31-38
Author(s):  
X. Zhao ◽  
Y. Itoh ◽  
Y. Aoyagi ◽  
T. Sugano ◽  
K. Hirata ◽  
...  
Keyword(s):  
Thin Films ◽  
Nanocrystalline Silicon ◽  
Silicon Thin Films ◽  
Positronium Annihilation

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

Study of Pore Property of Mesoporous Films Materials for Trace Explosive Detection

2013 ◽  
Vol 743-744 ◽  
pp. 397-401 ◽  
Author(s):  
Li Ma ◽  
Yu Quan Wen ◽  
Nan Yan ◽  
Guang Tao Li
Keyword(s):  
Thin Films ◽  
Pore Structure ◽  
Sol Gel ◽  
High Sensitivity ◽  
Pluronic F127 ◽  
Structure Directing Agent ◽  
Pore Property ◽  
Mesoporous Film ◽  
Quenching Efficiency ◽  
Fluorescence Dye

Thus, here, by using the sol-gel technique and spin coating technology, a series of mesoporous silica thin films doped by silylated naphthol fluorescence dye were successfully fabricated. By selecting the same surfactant triblock copolymer Pluronic F127 (EO106-PO70-EO106) as structure-directing agent, films with different pore structure and similar aperture size were synthesized under different conditions. The films doping fluorescence dye toward nitro explosive 2, 4, 6-trinitrotoluene (TNT) vapor exhibited rapid response rate and extremely high fluorescent quenching efficiency, close to 96.4 % after 1200 s response. The results clearly showed that pore structure control of mesoporous film was an effective way to improve sensor performance. Mesoporous thin films, with different pore structure, easily to be prepared and owning high sensitivity, could be used as a new alternative of trace explosive detecting material.

Sign in / Sign up

Export Citation Format

Share Document